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nEPT: Support shadow paging for guest paging without A/D bits

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Some guest paging modes do not support A/D bits. Add support for such
modes in shadow page code. For such modes PT_GUEST_DIRTY_MASK,
PT_GUEST_ACCESSED_MASK, PT_GUEST_DIRTY_SHIFT and PT_GUEST_ACCESSED_SHIFT
should be set to zero.

Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Gleb Natapov 2013-08-05 11:07:11 +03:00 committed by Paolo Bonzini
parent d8089baca4
commit 61719a8fff
1 changed files with 13 additions and 3 deletions
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16
arch/x86/kvm/paging_tmpl.h
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@ -92,6 +92,10 @@ static inline void FNAME(protect_clean_gpte)(unsigned *access, unsigned gpte)
{
unsigned mask;
/* dirty bit is not supported, so no need to track it */
if (!PT_GUEST_DIRTY_MASK)
return;
BUILD_BUG_ON(PT_WRITABLE_MASK != ACC_WRITE_MASK);
mask = (unsigned)~ACC_WRITE_MASK;
@ -147,7 +151,8 @@ static bool FNAME(prefetch_invalid_gpte)(struct kvm_vcpu *vcpu,
if (!FNAME(is_present_gpte)(gpte))
goto no_present;
if (!(gpte & PT_GUEST_ACCESSED_MASK))
/* if accessed bit is not supported prefetch non accessed gpte */
if (PT_GUEST_ACCESSED_MASK && !(gpte & PT_GUEST_ACCESSED_MASK))
goto no_present;
return false;
@ -178,6 +183,10 @@ static int FNAME(update_accessed_dirty_bits)(struct kvm_vcpu *vcpu,
gfn_t table_gfn;
int ret;
/* dirty/accessed bits are not supported, so no need to update them */
if (!PT_GUEST_DIRTY_MASK)
return 0;
for (level = walker->max_level; level >= walker->level; --level) {
pte = orig_pte = walker->ptes[level - 1];
table_gfn = walker->table_gfn[level - 1];
@ -316,8 +325,9 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
FNAME(protect_clean_gpte)(&pte_access, pte);
else
/*
* On a write fault, fold the dirty bit into accessed_dirty by
* shifting it one place right.
* On a write fault, fold the dirty bit into accessed_dirty.
* For modes without A/D bits support accessed_dirty will be
* always clear.
*/
accessed_dirty &= pte >>
(PT_GUEST_DIRTY_SHIFT - PT_GUEST_ACCESSED_SHIFT);