2fc136eecd
If the caller passes a valid kmap_op to m2p_add_override, we use kmap_op->dev_bus_addr to store the original mfn, but dev_bus_addr is part of the interface with Xen and if we are batching the hypercalls it might not have been written by the hypervisor yet. That means that later on Xen will write to it and we'll think that the original mfn is actually what Xen has written to it. Rather than "stealing" struct members from kmap_op, keep using page->index to store the original mfn and add another parameter to m2p_remove_override to get the corresponding kmap_op instead. It is now responsibility of the caller to keep track of which kmap_op corresponds to a particular page in the m2p_override (gntdev, the only user of this interface that passes a valid kmap_op, is already doing that). CC: stable@kernel.org Reported-and-Tested-By: Sander Eikelenboom <linux@eikelenboom.it> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
1094 lines
33 KiB
C
1094 lines
33 KiB
C
/*
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* Xen leaves the responsibility for maintaining p2m mappings to the
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* guests themselves, but it must also access and update the p2m array
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* during suspend/resume when all the pages are reallocated.
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*
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* The p2m table is logically a flat array, but we implement it as a
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* three-level tree to allow the address space to be sparse.
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*
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* Xen
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* |
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* p2m_top p2m_top_mfn
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* / \ / \
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* p2m_mid p2m_mid p2m_mid_mfn p2m_mid_mfn
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* / \ / \ / /
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* p2m p2m p2m p2m p2m p2m p2m ...
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*
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* The p2m_mid_mfn pages are mapped by p2m_top_mfn_p.
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*
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* The p2m_top and p2m_top_mfn levels are limited to 1 page, so the
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* maximum representable pseudo-physical address space is:
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* P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE pages
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*
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* P2M_PER_PAGE depends on the architecture, as a mfn is always
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* unsigned long (8 bytes on 64-bit, 4 bytes on 32), leading to
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* 512 and 1024 entries respectively.
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*
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* In short, these structures contain the Machine Frame Number (MFN) of the PFN.
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*
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* However not all entries are filled with MFNs. Specifically for all other
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* leaf entries, or for the top root, or middle one, for which there is a void
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* entry, we assume it is "missing". So (for example)
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* pfn_to_mfn(0x90909090)=INVALID_P2M_ENTRY.
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*
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* We also have the possibility of setting 1-1 mappings on certain regions, so
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* that:
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* pfn_to_mfn(0xc0000)=0xc0000
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*
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* The benefit of this is, that we can assume for non-RAM regions (think
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* PCI BARs, or ACPI spaces), we can create mappings easily b/c we
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* get the PFN value to match the MFN.
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*
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* For this to work efficiently we have one new page p2m_identity and
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* allocate (via reserved_brk) any other pages we need to cover the sides
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* (1GB or 4MB boundary violations). All entries in p2m_identity are set to
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* INVALID_P2M_ENTRY type (Xen toolstack only recognizes that and MFNs,
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* no other fancy value).
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*
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* On lookup we spot that the entry points to p2m_identity and return the
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* identity value instead of dereferencing and returning INVALID_P2M_ENTRY.
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* If the entry points to an allocated page, we just proceed as before and
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* return the PFN. If the PFN has IDENTITY_FRAME_BIT set we unmask that in
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* appropriate functions (pfn_to_mfn).
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*
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* The reason for having the IDENTITY_FRAME_BIT instead of just returning the
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* PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
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* non-identity pfn. To protect ourselves against we elect to set (and get) the
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* IDENTITY_FRAME_BIT on all identity mapped PFNs.
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*
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* This simplistic diagram is used to explain the more subtle piece of code.
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* There is also a digram of the P2M at the end that can help.
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* Imagine your E820 looking as so:
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*
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* 1GB 2GB
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* /-------------------+---------\/----\ /----------\ /---+-----\
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* | System RAM | Sys RAM ||ACPI| | reserved | | Sys RAM |
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* \-------------------+---------/\----/ \----------/ \---+-----/
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* ^- 1029MB ^- 2001MB
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*
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* [1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100),
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* 2048MB = 524288 (0x80000)]
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*
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* And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
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* is actually not present (would have to kick the balloon driver to put it in).
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*
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* When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
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* Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
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* of the PFN and the end PFN (263424 and 512256 respectively). The first step
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* is to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
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* covers 512^2 of page estate (1GB) and in case the start or end PFN is not
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* aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn
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* to end pfn. We reserve_brk top leaf pages if they are missing (means they
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* point to p2m_mid_missing).
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*
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* With the E820 example above, 263424 is not 1GB aligned so we allocate a
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* reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
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* Each entry in the allocate page is "missing" (points to p2m_missing).
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*
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* Next stage is to determine if we need to do a more granular boundary check
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* on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
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* We check if the start pfn and end pfn violate that boundary check, and if
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* so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
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* granularity of setting which PFNs are missing and which ones are identity.
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* In our example 263424 and 512256 both fail the check so we reserve_brk two
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* pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing"
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* values) and assign them to p2m[1][2] and p2m[1][488] respectively.
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*
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* At this point we would at minimum reserve_brk one page, but could be up to
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* three. Each call to set_phys_range_identity has at maximum a three page
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* cost. If we were to query the P2M at this stage, all those entries from
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* start PFN through end PFN (so 1029MB -> 2001MB) would return
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* INVALID_P2M_ENTRY ("missing").
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*
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* The next step is to walk from the start pfn to the end pfn setting
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* the IDENTITY_FRAME_BIT on each PFN. This is done in set_phys_range_identity.
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* If we find that the middle leaf is pointing to p2m_missing we can swap it
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* over to p2m_identity - this way covering 4MB (or 2MB) PFN space. At this
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* point we do not need to worry about boundary aligment (so no need to
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* reserve_brk a middle page, figure out which PFNs are "missing" and which
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* ones are identity), as that has been done earlier. If we find that the
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* middle leaf is not occupied by p2m_identity or p2m_missing, we dereference
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* that page (which covers 512 PFNs) and set the appropriate PFN with
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* IDENTITY_FRAME_BIT. In our example 263424 and 512256 end up there, and we
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* set from p2m[1][2][256->511] and p2m[1][488][0->256] with
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* IDENTITY_FRAME_BIT set.
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*
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* All other regions that are void (or not filled) either point to p2m_missing
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* (considered missing) or have the default value of INVALID_P2M_ENTRY (also
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* considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
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* contain the INVALID_P2M_ENTRY value and are considered "missing."
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*
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* This is what the p2m ends up looking (for the E820 above) with this
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* fabulous drawing:
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*
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* p2m /--------------\
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* /-----\ | &mfn_list[0],| /-----------------\
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* | 0 |------>| &mfn_list[1],| /---------------\ | ~0, ~0, .. |
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* |-----| | ..., ~0, ~0 | | ~0, ~0, [x]---+----->| IDENTITY [@256] |
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* | 1 |---\ \--------------/ | [p2m_identity]+\ | IDENTITY [@257] |
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* |-----| \ | [p2m_identity]+\\ | .... |
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* | 2 |--\ \-------------------->| ... | \\ \----------------/
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* |-----| \ \---------------/ \\
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* | 3 |\ \ \\ p2m_identity
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* |-----| \ \-------------------->/---------------\ /-----------------\
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* | .. +->+ | [p2m_identity]+-->| ~0, ~0, ~0, ... |
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* \-----/ / | [p2m_identity]+-->| ..., ~0 |
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* / /---------------\ | .... | \-----------------/
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* / | IDENTITY[@0] | /-+-[x], ~0, ~0.. |
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* / | IDENTITY[@256]|<----/ \---------------/
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* / | ~0, ~0, .... |
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* | \---------------/
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* |
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* p2m_missing p2m_missing
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* /------------------\ /------------\
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* | [p2m_mid_missing]+---->| ~0, ~0, ~0 |
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* | [p2m_mid_missing]+---->| ..., ~0 |
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* \------------------/ \------------/
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*
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* where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/list.h>
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#include <linux/hash.h>
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#include <linux/sched.h>
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#include <linux/seq_file.h>
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#include <asm/cache.h>
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#include <asm/setup.h>
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#include <asm/xen/page.h>
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#include <asm/xen/hypercall.h>
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#include <asm/xen/hypervisor.h>
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#include <xen/grant_table.h>
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#include "multicalls.h"
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#include "xen-ops.h"
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static void __init m2p_override_init(void);
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unsigned long xen_max_p2m_pfn __read_mostly;
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#define P2M_PER_PAGE (PAGE_SIZE / sizeof(unsigned long))
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#define P2M_MID_PER_PAGE (PAGE_SIZE / sizeof(unsigned long *))
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#define P2M_TOP_PER_PAGE (PAGE_SIZE / sizeof(unsigned long **))
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#define MAX_P2M_PFN (P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE)
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/* Placeholders for holes in the address space */
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static RESERVE_BRK_ARRAY(unsigned long, p2m_missing, P2M_PER_PAGE);
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static RESERVE_BRK_ARRAY(unsigned long *, p2m_mid_missing, P2M_MID_PER_PAGE);
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static RESERVE_BRK_ARRAY(unsigned long, p2m_mid_missing_mfn, P2M_MID_PER_PAGE);
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static RESERVE_BRK_ARRAY(unsigned long **, p2m_top, P2M_TOP_PER_PAGE);
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static RESERVE_BRK_ARRAY(unsigned long, p2m_top_mfn, P2M_TOP_PER_PAGE);
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static RESERVE_BRK_ARRAY(unsigned long *, p2m_top_mfn_p, P2M_TOP_PER_PAGE);
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static RESERVE_BRK_ARRAY(unsigned long, p2m_identity, P2M_PER_PAGE);
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RESERVE_BRK(p2m_mid, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));
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RESERVE_BRK(p2m_mid_mfn, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));
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/* We might hit two boundary violations at the start and end, at max each
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* boundary violation will require three middle nodes. */
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RESERVE_BRK(p2m_mid_identity, PAGE_SIZE * 2 * 3);
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/* When we populate back during bootup, the amount of pages can vary. The
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* max we have is seen is 395979, but that does not mean it can't be more.
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* Some machines can have 3GB I/O holes even. With early_can_reuse_p2m_middle
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* it can re-use Xen provided mfn_list array, so we only need to allocate at
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* most three P2M top nodes. */
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RESERVE_BRK(p2m_populated, PAGE_SIZE * 3);
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static inline unsigned p2m_top_index(unsigned long pfn)
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{
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BUG_ON(pfn >= MAX_P2M_PFN);
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return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE);
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}
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static inline unsigned p2m_mid_index(unsigned long pfn)
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{
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return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE;
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}
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static inline unsigned p2m_index(unsigned long pfn)
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{
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return pfn % P2M_PER_PAGE;
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}
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static void p2m_top_init(unsigned long ***top)
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{
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unsigned i;
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for (i = 0; i < P2M_TOP_PER_PAGE; i++)
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top[i] = p2m_mid_missing;
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}
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static void p2m_top_mfn_init(unsigned long *top)
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{
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unsigned i;
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for (i = 0; i < P2M_TOP_PER_PAGE; i++)
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top[i] = virt_to_mfn(p2m_mid_missing_mfn);
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}
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static void p2m_top_mfn_p_init(unsigned long **top)
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{
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unsigned i;
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for (i = 0; i < P2M_TOP_PER_PAGE; i++)
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top[i] = p2m_mid_missing_mfn;
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}
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static void p2m_mid_init(unsigned long **mid)
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{
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unsigned i;
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for (i = 0; i < P2M_MID_PER_PAGE; i++)
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mid[i] = p2m_missing;
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}
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static void p2m_mid_mfn_init(unsigned long *mid)
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{
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unsigned i;
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for (i = 0; i < P2M_MID_PER_PAGE; i++)
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mid[i] = virt_to_mfn(p2m_missing);
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}
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static void p2m_init(unsigned long *p2m)
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{
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unsigned i;
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for (i = 0; i < P2M_MID_PER_PAGE; i++)
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p2m[i] = INVALID_P2M_ENTRY;
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}
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/*
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* Build the parallel p2m_top_mfn and p2m_mid_mfn structures
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*
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* This is called both at boot time, and after resuming from suspend:
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* - At boot time we're called very early, and must use extend_brk()
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* to allocate memory.
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*
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* - After resume we're called from within stop_machine, but the mfn
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* tree should alreay be completely allocated.
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*/
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void __ref xen_build_mfn_list_list(void)
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{
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unsigned long pfn;
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/* Pre-initialize p2m_top_mfn to be completely missing */
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if (p2m_top_mfn == NULL) {
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p2m_mid_missing_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
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p2m_mid_mfn_init(p2m_mid_missing_mfn);
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p2m_top_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
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p2m_top_mfn_p_init(p2m_top_mfn_p);
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p2m_top_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
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p2m_top_mfn_init(p2m_top_mfn);
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} else {
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/* Reinitialise, mfn's all change after migration */
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p2m_mid_mfn_init(p2m_mid_missing_mfn);
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}
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for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += P2M_PER_PAGE) {
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unsigned topidx = p2m_top_index(pfn);
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unsigned mididx = p2m_mid_index(pfn);
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unsigned long **mid;
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unsigned long *mid_mfn_p;
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mid = p2m_top[topidx];
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mid_mfn_p = p2m_top_mfn_p[topidx];
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/* Don't bother allocating any mfn mid levels if
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* they're just missing, just update the stored mfn,
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* since all could have changed over a migrate.
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*/
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if (mid == p2m_mid_missing) {
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BUG_ON(mididx);
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BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
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p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn);
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pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE;
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continue;
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}
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if (mid_mfn_p == p2m_mid_missing_mfn) {
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/*
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* XXX boot-time only! We should never find
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* missing parts of the mfn tree after
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* runtime. extend_brk() will BUG if we call
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* it too late.
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*/
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mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
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p2m_mid_mfn_init(mid_mfn_p);
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p2m_top_mfn_p[topidx] = mid_mfn_p;
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}
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p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
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mid_mfn_p[mididx] = virt_to_mfn(mid[mididx]);
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}
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}
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void xen_setup_mfn_list_list(void)
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{
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BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
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HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list =
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virt_to_mfn(p2m_top_mfn);
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HYPERVISOR_shared_info->arch.max_pfn = xen_max_p2m_pfn;
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}
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/* Set up p2m_top to point to the domain-builder provided p2m pages */
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void __init xen_build_dynamic_phys_to_machine(void)
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{
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unsigned long *mfn_list = (unsigned long *)xen_start_info->mfn_list;
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unsigned long max_pfn = min(MAX_DOMAIN_PAGES, xen_start_info->nr_pages);
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unsigned long pfn;
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xen_max_p2m_pfn = max_pfn;
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p2m_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
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p2m_init(p2m_missing);
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p2m_mid_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
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p2m_mid_init(p2m_mid_missing);
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p2m_top = extend_brk(PAGE_SIZE, PAGE_SIZE);
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p2m_top_init(p2m_top);
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p2m_identity = extend_brk(PAGE_SIZE, PAGE_SIZE);
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p2m_init(p2m_identity);
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/*
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* The domain builder gives us a pre-constructed p2m array in
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* mfn_list for all the pages initially given to us, so we just
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* need to graft that into our tree structure.
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*/
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for (pfn = 0; pfn < max_pfn; pfn += P2M_PER_PAGE) {
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unsigned topidx = p2m_top_index(pfn);
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unsigned mididx = p2m_mid_index(pfn);
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if (p2m_top[topidx] == p2m_mid_missing) {
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unsigned long **mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
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p2m_mid_init(mid);
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p2m_top[topidx] = mid;
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}
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/*
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* As long as the mfn_list has enough entries to completely
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* fill a p2m page, pointing into the array is ok. But if
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* not the entries beyond the last pfn will be undefined.
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*/
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if (unlikely(pfn + P2M_PER_PAGE > max_pfn)) {
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unsigned long p2midx;
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p2midx = max_pfn % P2M_PER_PAGE;
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for ( ; p2midx < P2M_PER_PAGE; p2midx++)
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mfn_list[pfn + p2midx] = INVALID_P2M_ENTRY;
|
|
}
|
|
p2m_top[topidx][mididx] = &mfn_list[pfn];
|
|
}
|
|
|
|
m2p_override_init();
|
|
}
|
|
|
|
unsigned long get_phys_to_machine(unsigned long pfn)
|
|
{
|
|
unsigned topidx, mididx, idx;
|
|
|
|
if (unlikely(pfn >= MAX_P2M_PFN))
|
|
return INVALID_P2M_ENTRY;
|
|
|
|
topidx = p2m_top_index(pfn);
|
|
mididx = p2m_mid_index(pfn);
|
|
idx = p2m_index(pfn);
|
|
|
|
/*
|
|
* The INVALID_P2M_ENTRY is filled in both p2m_*identity
|
|
* and in p2m_*missing, so returning the INVALID_P2M_ENTRY
|
|
* would be wrong.
|
|
*/
|
|
if (p2m_top[topidx][mididx] == p2m_identity)
|
|
return IDENTITY_FRAME(pfn);
|
|
|
|
return p2m_top[topidx][mididx][idx];
|
|
}
|
|
EXPORT_SYMBOL_GPL(get_phys_to_machine);
|
|
|
|
static void *alloc_p2m_page(void)
|
|
{
|
|
return (void *)__get_free_page(GFP_KERNEL | __GFP_REPEAT);
|
|
}
|
|
|
|
static void free_p2m_page(void *p)
|
|
{
|
|
free_page((unsigned long)p);
|
|
}
|
|
|
|
/*
|
|
* Fully allocate the p2m structure for a given pfn. We need to check
|
|
* that both the top and mid levels are allocated, and make sure the
|
|
* parallel mfn tree is kept in sync. We may race with other cpus, so
|
|
* the new pages are installed with cmpxchg; if we lose the race then
|
|
* simply free the page we allocated and use the one that's there.
|
|
*/
|
|
static bool alloc_p2m(unsigned long pfn)
|
|
{
|
|
unsigned topidx, mididx;
|
|
unsigned long ***top_p, **mid;
|
|
unsigned long *top_mfn_p, *mid_mfn;
|
|
|
|
topidx = p2m_top_index(pfn);
|
|
mididx = p2m_mid_index(pfn);
|
|
|
|
top_p = &p2m_top[topidx];
|
|
mid = *top_p;
|
|
|
|
if (mid == p2m_mid_missing) {
|
|
/* Mid level is missing, allocate a new one */
|
|
mid = alloc_p2m_page();
|
|
if (!mid)
|
|
return false;
|
|
|
|
p2m_mid_init(mid);
|
|
|
|
if (cmpxchg(top_p, p2m_mid_missing, mid) != p2m_mid_missing)
|
|
free_p2m_page(mid);
|
|
}
|
|
|
|
top_mfn_p = &p2m_top_mfn[topidx];
|
|
mid_mfn = p2m_top_mfn_p[topidx];
|
|
|
|
BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
|
|
|
|
if (mid_mfn == p2m_mid_missing_mfn) {
|
|
/* Separately check the mid mfn level */
|
|
unsigned long missing_mfn;
|
|
unsigned long mid_mfn_mfn;
|
|
|
|
mid_mfn = alloc_p2m_page();
|
|
if (!mid_mfn)
|
|
return false;
|
|
|
|
p2m_mid_mfn_init(mid_mfn);
|
|
|
|
missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
|
|
mid_mfn_mfn = virt_to_mfn(mid_mfn);
|
|
if (cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn) != missing_mfn)
|
|
free_p2m_page(mid_mfn);
|
|
else
|
|
p2m_top_mfn_p[topidx] = mid_mfn;
|
|
}
|
|
|
|
if (p2m_top[topidx][mididx] == p2m_identity ||
|
|
p2m_top[topidx][mididx] == p2m_missing) {
|
|
/* p2m leaf page is missing */
|
|
unsigned long *p2m;
|
|
unsigned long *p2m_orig = p2m_top[topidx][mididx];
|
|
|
|
p2m = alloc_p2m_page();
|
|
if (!p2m)
|
|
return false;
|
|
|
|
p2m_init(p2m);
|
|
|
|
if (cmpxchg(&mid[mididx], p2m_orig, p2m) != p2m_orig)
|
|
free_p2m_page(p2m);
|
|
else
|
|
mid_mfn[mididx] = virt_to_mfn(p2m);
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
static bool __init early_alloc_p2m_middle(unsigned long pfn, bool check_boundary)
|
|
{
|
|
unsigned topidx, mididx, idx;
|
|
unsigned long *p2m;
|
|
unsigned long *mid_mfn_p;
|
|
|
|
topidx = p2m_top_index(pfn);
|
|
mididx = p2m_mid_index(pfn);
|
|
idx = p2m_index(pfn);
|
|
|
|
/* Pfff.. No boundary cross-over, lets get out. */
|
|
if (!idx && check_boundary)
|
|
return false;
|
|
|
|
WARN(p2m_top[topidx][mididx] == p2m_identity,
|
|
"P2M[%d][%d] == IDENTITY, should be MISSING (or alloced)!\n",
|
|
topidx, mididx);
|
|
|
|
/*
|
|
* Could be done by xen_build_dynamic_phys_to_machine..
|
|
*/
|
|
if (p2m_top[topidx][mididx] != p2m_missing)
|
|
return false;
|
|
|
|
/* Boundary cross-over for the edges: */
|
|
p2m = extend_brk(PAGE_SIZE, PAGE_SIZE);
|
|
|
|
p2m_init(p2m);
|
|
|
|
p2m_top[topidx][mididx] = p2m;
|
|
|
|
/* For save/restore we need to MFN of the P2M saved */
|
|
|
|
mid_mfn_p = p2m_top_mfn_p[topidx];
|
|
WARN(mid_mfn_p[mididx] != virt_to_mfn(p2m_missing),
|
|
"P2M_TOP_P[%d][%d] != MFN of p2m_missing!\n",
|
|
topidx, mididx);
|
|
mid_mfn_p[mididx] = virt_to_mfn(p2m);
|
|
|
|
return true;
|
|
}
|
|
|
|
static bool __init early_alloc_p2m(unsigned long pfn)
|
|
{
|
|
unsigned topidx = p2m_top_index(pfn);
|
|
unsigned long *mid_mfn_p;
|
|
unsigned long **mid;
|
|
|
|
mid = p2m_top[topidx];
|
|
mid_mfn_p = p2m_top_mfn_p[topidx];
|
|
if (mid == p2m_mid_missing) {
|
|
mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
|
|
|
|
p2m_mid_init(mid);
|
|
|
|
p2m_top[topidx] = mid;
|
|
|
|
BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
|
|
}
|
|
/* And the save/restore P2M tables.. */
|
|
if (mid_mfn_p == p2m_mid_missing_mfn) {
|
|
mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
|
|
p2m_mid_mfn_init(mid_mfn_p);
|
|
|
|
p2m_top_mfn_p[topidx] = mid_mfn_p;
|
|
p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
|
|
/* Note: we don't set mid_mfn_p[midix] here,
|
|
* look in early_alloc_p2m_middle */
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Skim over the P2M tree looking at pages that are either filled with
|
|
* INVALID_P2M_ENTRY or with 1:1 PFNs. If found, re-use that page and
|
|
* replace the P2M leaf with a p2m_missing or p2m_identity.
|
|
* Stick the old page in the new P2M tree location.
|
|
*/
|
|
bool __init early_can_reuse_p2m_middle(unsigned long set_pfn, unsigned long set_mfn)
|
|
{
|
|
unsigned topidx;
|
|
unsigned mididx;
|
|
unsigned ident_pfns;
|
|
unsigned inv_pfns;
|
|
unsigned long *p2m;
|
|
unsigned long *mid_mfn_p;
|
|
unsigned idx;
|
|
unsigned long pfn;
|
|
|
|
/* We only look when this entails a P2M middle layer */
|
|
if (p2m_index(set_pfn))
|
|
return false;
|
|
|
|
for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn += P2M_PER_PAGE) {
|
|
topidx = p2m_top_index(pfn);
|
|
|
|
if (!p2m_top[topidx])
|
|
continue;
|
|
|
|
if (p2m_top[topidx] == p2m_mid_missing)
|
|
continue;
|
|
|
|
mididx = p2m_mid_index(pfn);
|
|
p2m = p2m_top[topidx][mididx];
|
|
if (!p2m)
|
|
continue;
|
|
|
|
if ((p2m == p2m_missing) || (p2m == p2m_identity))
|
|
continue;
|
|
|
|
if ((unsigned long)p2m == INVALID_P2M_ENTRY)
|
|
continue;
|
|
|
|
ident_pfns = 0;
|
|
inv_pfns = 0;
|
|
for (idx = 0; idx < P2M_PER_PAGE; idx++) {
|
|
/* IDENTITY_PFNs are 1:1 */
|
|
if (p2m[idx] == IDENTITY_FRAME(pfn + idx))
|
|
ident_pfns++;
|
|
else if (p2m[idx] == INVALID_P2M_ENTRY)
|
|
inv_pfns++;
|
|
else
|
|
break;
|
|
}
|
|
if ((ident_pfns == P2M_PER_PAGE) || (inv_pfns == P2M_PER_PAGE))
|
|
goto found;
|
|
}
|
|
return false;
|
|
found:
|
|
/* Found one, replace old with p2m_identity or p2m_missing */
|
|
p2m_top[topidx][mididx] = (ident_pfns ? p2m_identity : p2m_missing);
|
|
/* And the other for save/restore.. */
|
|
mid_mfn_p = p2m_top_mfn_p[topidx];
|
|
/* NOTE: Even if it is a p2m_identity it should still be point to
|
|
* a page filled with INVALID_P2M_ENTRY entries. */
|
|
mid_mfn_p[mididx] = virt_to_mfn(p2m_missing);
|
|
|
|
/* Reset where we want to stick the old page in. */
|
|
topidx = p2m_top_index(set_pfn);
|
|
mididx = p2m_mid_index(set_pfn);
|
|
|
|
/* This shouldn't happen */
|
|
if (WARN_ON(p2m_top[topidx] == p2m_mid_missing))
|
|
early_alloc_p2m(set_pfn);
|
|
|
|
if (WARN_ON(p2m_top[topidx][mididx] != p2m_missing))
|
|
return false;
|
|
|
|
p2m_init(p2m);
|
|
p2m_top[topidx][mididx] = p2m;
|
|
mid_mfn_p = p2m_top_mfn_p[topidx];
|
|
mid_mfn_p[mididx] = virt_to_mfn(p2m);
|
|
|
|
return true;
|
|
}
|
|
bool __init early_set_phys_to_machine(unsigned long pfn, unsigned long mfn)
|
|
{
|
|
if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
|
|
if (!early_alloc_p2m(pfn))
|
|
return false;
|
|
|
|
if (early_can_reuse_p2m_middle(pfn, mfn))
|
|
return __set_phys_to_machine(pfn, mfn);
|
|
|
|
if (!early_alloc_p2m_middle(pfn, false /* boundary crossover OK!*/))
|
|
return false;
|
|
|
|
if (!__set_phys_to_machine(pfn, mfn))
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
unsigned long __init set_phys_range_identity(unsigned long pfn_s,
|
|
unsigned long pfn_e)
|
|
{
|
|
unsigned long pfn;
|
|
|
|
if (unlikely(pfn_s >= MAX_P2M_PFN || pfn_e >= MAX_P2M_PFN))
|
|
return 0;
|
|
|
|
if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
|
|
return pfn_e - pfn_s;
|
|
|
|
if (pfn_s > pfn_e)
|
|
return 0;
|
|
|
|
for (pfn = (pfn_s & ~(P2M_MID_PER_PAGE * P2M_PER_PAGE - 1));
|
|
pfn < ALIGN(pfn_e, (P2M_MID_PER_PAGE * P2M_PER_PAGE));
|
|
pfn += P2M_MID_PER_PAGE * P2M_PER_PAGE)
|
|
{
|
|
WARN_ON(!early_alloc_p2m(pfn));
|
|
}
|
|
|
|
early_alloc_p2m_middle(pfn_s, true);
|
|
early_alloc_p2m_middle(pfn_e, true);
|
|
|
|
for (pfn = pfn_s; pfn < pfn_e; pfn++)
|
|
if (!__set_phys_to_machine(pfn, IDENTITY_FRAME(pfn)))
|
|
break;
|
|
|
|
if (!WARN((pfn - pfn_s) != (pfn_e - pfn_s),
|
|
"Identity mapping failed. We are %ld short of 1-1 mappings!\n",
|
|
(pfn_e - pfn_s) - (pfn - pfn_s)))
|
|
printk(KERN_DEBUG "1-1 mapping on %lx->%lx\n", pfn_s, pfn);
|
|
|
|
return pfn - pfn_s;
|
|
}
|
|
|
|
/* Try to install p2m mapping; fail if intermediate bits missing */
|
|
bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
|
|
{
|
|
unsigned topidx, mididx, idx;
|
|
|
|
if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) {
|
|
BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY);
|
|
return true;
|
|
}
|
|
if (unlikely(pfn >= MAX_P2M_PFN)) {
|
|
BUG_ON(mfn != INVALID_P2M_ENTRY);
|
|
return true;
|
|
}
|
|
|
|
topidx = p2m_top_index(pfn);
|
|
mididx = p2m_mid_index(pfn);
|
|
idx = p2m_index(pfn);
|
|
|
|
/* For sparse holes were the p2m leaf has real PFN along with
|
|
* PCI holes, stick in the PFN as the MFN value.
|
|
*/
|
|
if (mfn != INVALID_P2M_ENTRY && (mfn & IDENTITY_FRAME_BIT)) {
|
|
if (p2m_top[topidx][mididx] == p2m_identity)
|
|
return true;
|
|
|
|
/* Swap over from MISSING to IDENTITY if needed. */
|
|
if (p2m_top[topidx][mididx] == p2m_missing) {
|
|
WARN_ON(cmpxchg(&p2m_top[topidx][mididx], p2m_missing,
|
|
p2m_identity) != p2m_missing);
|
|
return true;
|
|
}
|
|
}
|
|
|
|
if (p2m_top[topidx][mididx] == p2m_missing)
|
|
return mfn == INVALID_P2M_ENTRY;
|
|
|
|
p2m_top[topidx][mididx][idx] = mfn;
|
|
|
|
return true;
|
|
}
|
|
|
|
bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
|
|
{
|
|
if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
|
|
if (!alloc_p2m(pfn))
|
|
return false;
|
|
|
|
if (!__set_phys_to_machine(pfn, mfn))
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
#define M2P_OVERRIDE_HASH_SHIFT 10
|
|
#define M2P_OVERRIDE_HASH (1 << M2P_OVERRIDE_HASH_SHIFT)
|
|
|
|
static RESERVE_BRK_ARRAY(struct list_head, m2p_overrides, M2P_OVERRIDE_HASH);
|
|
static DEFINE_SPINLOCK(m2p_override_lock);
|
|
|
|
static void __init m2p_override_init(void)
|
|
{
|
|
unsigned i;
|
|
|
|
m2p_overrides = extend_brk(sizeof(*m2p_overrides) * M2P_OVERRIDE_HASH,
|
|
sizeof(unsigned long));
|
|
|
|
for (i = 0; i < M2P_OVERRIDE_HASH; i++)
|
|
INIT_LIST_HEAD(&m2p_overrides[i]);
|
|
}
|
|
|
|
static unsigned long mfn_hash(unsigned long mfn)
|
|
{
|
|
return hash_long(mfn, M2P_OVERRIDE_HASH_SHIFT);
|
|
}
|
|
|
|
/* Add an MFN override for a particular page */
|
|
int m2p_add_override(unsigned long mfn, struct page *page,
|
|
struct gnttab_map_grant_ref *kmap_op)
|
|
{
|
|
unsigned long flags;
|
|
unsigned long pfn;
|
|
unsigned long uninitialized_var(address);
|
|
unsigned level;
|
|
pte_t *ptep = NULL;
|
|
int ret = 0;
|
|
|
|
pfn = page_to_pfn(page);
|
|
if (!PageHighMem(page)) {
|
|
address = (unsigned long)__va(pfn << PAGE_SHIFT);
|
|
ptep = lookup_address(address, &level);
|
|
if (WARN(ptep == NULL || level != PG_LEVEL_4K,
|
|
"m2p_add_override: pfn %lx not mapped", pfn))
|
|
return -EINVAL;
|
|
}
|
|
WARN_ON(PagePrivate(page));
|
|
SetPagePrivate(page);
|
|
set_page_private(page, mfn);
|
|
page->index = pfn_to_mfn(pfn);
|
|
|
|
if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn))))
|
|
return -ENOMEM;
|
|
|
|
if (kmap_op != NULL) {
|
|
if (!PageHighMem(page)) {
|
|
struct multicall_space mcs =
|
|
xen_mc_entry(sizeof(*kmap_op));
|
|
|
|
MULTI_grant_table_op(mcs.mc,
|
|
GNTTABOP_map_grant_ref, kmap_op, 1);
|
|
|
|
xen_mc_issue(PARAVIRT_LAZY_MMU);
|
|
}
|
|
}
|
|
spin_lock_irqsave(&m2p_override_lock, flags);
|
|
list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]);
|
|
spin_unlock_irqrestore(&m2p_override_lock, flags);
|
|
|
|
/* p2m(m2p(mfn)) == mfn: the mfn is already present somewhere in
|
|
* this domain. Set the FOREIGN_FRAME_BIT in the p2m for the other
|
|
* pfn so that the following mfn_to_pfn(mfn) calls will return the
|
|
* pfn from the m2p_override (the backend pfn) instead.
|
|
* We need to do this because the pages shared by the frontend
|
|
* (xen-blkfront) can be already locked (lock_page, called by
|
|
* do_read_cache_page); when the userspace backend tries to use them
|
|
* with direct_IO, mfn_to_pfn returns the pfn of the frontend, so
|
|
* do_blockdev_direct_IO is going to try to lock the same pages
|
|
* again resulting in a deadlock.
|
|
* As a side effect get_user_pages_fast might not be safe on the
|
|
* frontend pages while they are being shared with the backend,
|
|
* because mfn_to_pfn (that ends up being called by GUPF) will
|
|
* return the backend pfn rather than the frontend pfn. */
|
|
ret = __get_user(pfn, &machine_to_phys_mapping[mfn]);
|
|
if (ret == 0 && get_phys_to_machine(pfn) == mfn)
|
|
set_phys_to_machine(pfn, FOREIGN_FRAME(mfn));
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(m2p_add_override);
|
|
int m2p_remove_override(struct page *page,
|
|
struct gnttab_map_grant_ref *kmap_op)
|
|
{
|
|
unsigned long flags;
|
|
unsigned long mfn;
|
|
unsigned long pfn;
|
|
unsigned long uninitialized_var(address);
|
|
unsigned level;
|
|
pte_t *ptep = NULL;
|
|
int ret = 0;
|
|
|
|
pfn = page_to_pfn(page);
|
|
mfn = get_phys_to_machine(pfn);
|
|
if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT))
|
|
return -EINVAL;
|
|
|
|
if (!PageHighMem(page)) {
|
|
address = (unsigned long)__va(pfn << PAGE_SHIFT);
|
|
ptep = lookup_address(address, &level);
|
|
|
|
if (WARN(ptep == NULL || level != PG_LEVEL_4K,
|
|
"m2p_remove_override: pfn %lx not mapped", pfn))
|
|
return -EINVAL;
|
|
}
|
|
|
|
spin_lock_irqsave(&m2p_override_lock, flags);
|
|
list_del(&page->lru);
|
|
spin_unlock_irqrestore(&m2p_override_lock, flags);
|
|
WARN_ON(!PagePrivate(page));
|
|
ClearPagePrivate(page);
|
|
|
|
set_phys_to_machine(pfn, page->index);
|
|
if (kmap_op != NULL) {
|
|
if (!PageHighMem(page)) {
|
|
struct multicall_space mcs;
|
|
struct gnttab_unmap_grant_ref *unmap_op;
|
|
|
|
/*
|
|
* It might be that we queued all the m2p grant table
|
|
* hypercalls in a multicall, then m2p_remove_override
|
|
* get called before the multicall has actually been
|
|
* issued. In this case handle is going to -1 because
|
|
* it hasn't been modified yet.
|
|
*/
|
|
if (kmap_op->handle == -1)
|
|
xen_mc_flush();
|
|
/*
|
|
* Now if kmap_op->handle is negative it means that the
|
|
* hypercall actually returned an error.
|
|
*/
|
|
if (kmap_op->handle == GNTST_general_error) {
|
|
printk(KERN_WARNING "m2p_remove_override: "
|
|
"pfn %lx mfn %lx, failed to modify kernel mappings",
|
|
pfn, mfn);
|
|
return -1;
|
|
}
|
|
|
|
mcs = xen_mc_entry(
|
|
sizeof(struct gnttab_unmap_grant_ref));
|
|
unmap_op = mcs.args;
|
|
unmap_op->host_addr = kmap_op->host_addr;
|
|
unmap_op->handle = kmap_op->handle;
|
|
unmap_op->dev_bus_addr = 0;
|
|
|
|
MULTI_grant_table_op(mcs.mc,
|
|
GNTTABOP_unmap_grant_ref, unmap_op, 1);
|
|
|
|
xen_mc_issue(PARAVIRT_LAZY_MMU);
|
|
|
|
set_pte_at(&init_mm, address, ptep,
|
|
pfn_pte(pfn, PAGE_KERNEL));
|
|
__flush_tlb_single(address);
|
|
kmap_op->host_addr = 0;
|
|
}
|
|
}
|
|
|
|
/* p2m(m2p(mfn)) == FOREIGN_FRAME(mfn): the mfn is already present
|
|
* somewhere in this domain, even before being added to the
|
|
* m2p_override (see comment above in m2p_add_override).
|
|
* If there are no other entries in the m2p_override corresponding
|
|
* to this mfn, then remove the FOREIGN_FRAME_BIT from the p2m for
|
|
* the original pfn (the one shared by the frontend): the backend
|
|
* cannot do any IO on this page anymore because it has been
|
|
* unshared. Removing the FOREIGN_FRAME_BIT from the p2m entry of
|
|
* the original pfn causes mfn_to_pfn(mfn) to return the frontend
|
|
* pfn again. */
|
|
mfn &= ~FOREIGN_FRAME_BIT;
|
|
ret = __get_user(pfn, &machine_to_phys_mapping[mfn]);
|
|
if (ret == 0 && get_phys_to_machine(pfn) == FOREIGN_FRAME(mfn) &&
|
|
m2p_find_override(mfn) == NULL)
|
|
set_phys_to_machine(pfn, mfn);
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(m2p_remove_override);
|
|
|
|
struct page *m2p_find_override(unsigned long mfn)
|
|
{
|
|
unsigned long flags;
|
|
struct list_head *bucket = &m2p_overrides[mfn_hash(mfn)];
|
|
struct page *p, *ret;
|
|
|
|
ret = NULL;
|
|
|
|
spin_lock_irqsave(&m2p_override_lock, flags);
|
|
|
|
list_for_each_entry(p, bucket, lru) {
|
|
if (page_private(p) == mfn) {
|
|
ret = p;
|
|
break;
|
|
}
|
|
}
|
|
|
|
spin_unlock_irqrestore(&m2p_override_lock, flags);
|
|
|
|
return ret;
|
|
}
|
|
|
|
unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn)
|
|
{
|
|
struct page *p = m2p_find_override(mfn);
|
|
unsigned long ret = pfn;
|
|
|
|
if (p)
|
|
ret = page_to_pfn(p);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(m2p_find_override_pfn);
|
|
|
|
#ifdef CONFIG_XEN_DEBUG_FS
|
|
#include <linux/debugfs.h>
|
|
#include "debugfs.h"
|
|
static int p2m_dump_show(struct seq_file *m, void *v)
|
|
{
|
|
static const char * const level_name[] = { "top", "middle",
|
|
"entry", "abnormal", "error"};
|
|
#define TYPE_IDENTITY 0
|
|
#define TYPE_MISSING 1
|
|
#define TYPE_PFN 2
|
|
#define TYPE_UNKNOWN 3
|
|
static const char * const type_name[] = {
|
|
[TYPE_IDENTITY] = "identity",
|
|
[TYPE_MISSING] = "missing",
|
|
[TYPE_PFN] = "pfn",
|
|
[TYPE_UNKNOWN] = "abnormal"};
|
|
unsigned long pfn, prev_pfn_type = 0, prev_pfn_level = 0;
|
|
unsigned int uninitialized_var(prev_level);
|
|
unsigned int uninitialized_var(prev_type);
|
|
|
|
if (!p2m_top)
|
|
return 0;
|
|
|
|
for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn++) {
|
|
unsigned topidx = p2m_top_index(pfn);
|
|
unsigned mididx = p2m_mid_index(pfn);
|
|
unsigned idx = p2m_index(pfn);
|
|
unsigned lvl, type;
|
|
|
|
lvl = 4;
|
|
type = TYPE_UNKNOWN;
|
|
if (p2m_top[topidx] == p2m_mid_missing) {
|
|
lvl = 0; type = TYPE_MISSING;
|
|
} else if (p2m_top[topidx] == NULL) {
|
|
lvl = 0; type = TYPE_UNKNOWN;
|
|
} else if (p2m_top[topidx][mididx] == NULL) {
|
|
lvl = 1; type = TYPE_UNKNOWN;
|
|
} else if (p2m_top[topidx][mididx] == p2m_identity) {
|
|
lvl = 1; type = TYPE_IDENTITY;
|
|
} else if (p2m_top[topidx][mididx] == p2m_missing) {
|
|
lvl = 1; type = TYPE_MISSING;
|
|
} else if (p2m_top[topidx][mididx][idx] == 0) {
|
|
lvl = 2; type = TYPE_UNKNOWN;
|
|
} else if (p2m_top[topidx][mididx][idx] == IDENTITY_FRAME(pfn)) {
|
|
lvl = 2; type = TYPE_IDENTITY;
|
|
} else if (p2m_top[topidx][mididx][idx] == INVALID_P2M_ENTRY) {
|
|
lvl = 2; type = TYPE_MISSING;
|
|
} else if (p2m_top[topidx][mididx][idx] == pfn) {
|
|
lvl = 2; type = TYPE_PFN;
|
|
} else if (p2m_top[topidx][mididx][idx] != pfn) {
|
|
lvl = 2; type = TYPE_PFN;
|
|
}
|
|
if (pfn == 0) {
|
|
prev_level = lvl;
|
|
prev_type = type;
|
|
}
|
|
if (pfn == MAX_DOMAIN_PAGES-1) {
|
|
lvl = 3;
|
|
type = TYPE_UNKNOWN;
|
|
}
|
|
if (prev_type != type) {
|
|
seq_printf(m, " [0x%lx->0x%lx] %s\n",
|
|
prev_pfn_type, pfn, type_name[prev_type]);
|
|
prev_pfn_type = pfn;
|
|
prev_type = type;
|
|
}
|
|
if (prev_level != lvl) {
|
|
seq_printf(m, " [0x%lx->0x%lx] level %s\n",
|
|
prev_pfn_level, pfn, level_name[prev_level]);
|
|
prev_pfn_level = pfn;
|
|
prev_level = lvl;
|
|
}
|
|
}
|
|
return 0;
|
|
#undef TYPE_IDENTITY
|
|
#undef TYPE_MISSING
|
|
#undef TYPE_PFN
|
|
#undef TYPE_UNKNOWN
|
|
}
|
|
|
|
static int p2m_dump_open(struct inode *inode, struct file *filp)
|
|
{
|
|
return single_open(filp, p2m_dump_show, NULL);
|
|
}
|
|
|
|
static const struct file_operations p2m_dump_fops = {
|
|
.open = p2m_dump_open,
|
|
.read = seq_read,
|
|
.llseek = seq_lseek,
|
|
.release = single_release,
|
|
};
|
|
|
|
static struct dentry *d_mmu_debug;
|
|
|
|
static int __init xen_p2m_debugfs(void)
|
|
{
|
|
struct dentry *d_xen = xen_init_debugfs();
|
|
|
|
if (d_xen == NULL)
|
|
return -ENOMEM;
|
|
|
|
d_mmu_debug = debugfs_create_dir("mmu", d_xen);
|
|
|
|
debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops);
|
|
return 0;
|
|
}
|
|
fs_initcall(xen_p2m_debugfs);
|
|
#endif /* CONFIG_XEN_DEBUG_FS */
|