41408c28f2
On s390, we've got to make sure to hold the IPTE lock while accessing logical memory. So let's add an ioctl for reading and writing logical memory to provide this feature for userspace, too. The maximum transfer size of this call is limited to 64kB to prevent that the guest can trigger huge copy_from/to_user transfers. QEMU currently only requests up to one or two pages so far, so 16*4kB seems to be a reasonable limit here. Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
338 lines
12 KiB
C
338 lines
12 KiB
C
/*
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* access guest memory
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*
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* Copyright IBM Corp. 2008, 2014
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License (version 2 only)
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* as published by the Free Software Foundation.
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*
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* Author(s): Carsten Otte <cotte@de.ibm.com>
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*/
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#ifndef __KVM_S390_GACCESS_H
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#define __KVM_S390_GACCESS_H
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#include <linux/compiler.h>
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#include <linux/kvm_host.h>
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#include <linux/uaccess.h>
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#include <linux/ptrace.h>
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#include "kvm-s390.h"
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/**
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* kvm_s390_real_to_abs - convert guest real address to guest absolute address
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* @vcpu - guest virtual cpu
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* @gra - guest real address
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*
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* Returns the guest absolute address that corresponds to the passed guest real
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* address @gra of a virtual guest cpu by applying its prefix.
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*/
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static inline unsigned long kvm_s390_real_to_abs(struct kvm_vcpu *vcpu,
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unsigned long gra)
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{
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unsigned long prefix = kvm_s390_get_prefix(vcpu);
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if (gra < 2 * PAGE_SIZE)
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gra += prefix;
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else if (gra >= prefix && gra < prefix + 2 * PAGE_SIZE)
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gra -= prefix;
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return gra;
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}
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/**
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* kvm_s390_logical_to_effective - convert guest logical to effective address
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* @vcpu: guest virtual cpu
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* @ga: guest logical address
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*
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* Convert a guest vcpu logical address to a guest vcpu effective address by
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* applying the rules of the vcpu's addressing mode defined by PSW bits 31
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* and 32 (extendended/basic addressing mode).
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*
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* Depending on the vcpu's addressing mode the upper 40 bits (24 bit addressing
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* mode), 33 bits (31 bit addressing mode) or no bits (64 bit addressing mode)
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* of @ga will be zeroed and the remaining bits will be returned.
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*/
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static inline unsigned long kvm_s390_logical_to_effective(struct kvm_vcpu *vcpu,
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unsigned long ga)
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{
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psw_t *psw = &vcpu->arch.sie_block->gpsw;
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if (psw_bits(*psw).eaba == PSW_AMODE_64BIT)
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return ga;
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if (psw_bits(*psw).eaba == PSW_AMODE_31BIT)
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return ga & ((1UL << 31) - 1);
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return ga & ((1UL << 24) - 1);
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}
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/*
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* put_guest_lc, read_guest_lc and write_guest_lc are guest access functions
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* which shall only be used to access the lowcore of a vcpu.
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* These functions should be used for e.g. interrupt handlers where no
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* guest memory access protection facilities, like key or low address
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* protection, are applicable.
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* At a later point guest vcpu lowcore access should happen via pinned
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* prefix pages, so that these pages can be accessed directly via the
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* kernel mapping. All of these *_lc functions can be removed then.
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*/
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/**
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* put_guest_lc - write a simple variable to a guest vcpu's lowcore
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* @vcpu: virtual cpu
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* @x: value to copy to guest
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* @gra: vcpu's destination guest real address
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*
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* Copies a simple value from kernel space to a guest vcpu's lowcore.
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* The size of the variable may be 1, 2, 4 or 8 bytes. The destination
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* must be located in the vcpu's lowcore. Otherwise the result is undefined.
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*
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* Returns zero on success or -EFAULT on error.
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*
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* Note: an error indicates that either the kernel is out of memory or
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* the guest memory mapping is broken. In any case the best solution
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* would be to terminate the guest.
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* It is wrong to inject a guest exception.
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*/
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#define put_guest_lc(vcpu, x, gra) \
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({ \
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struct kvm_vcpu *__vcpu = (vcpu); \
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__typeof__(*(gra)) __x = (x); \
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unsigned long __gpa; \
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\
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__gpa = (unsigned long)(gra); \
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__gpa += kvm_s390_get_prefix(__vcpu); \
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kvm_write_guest(__vcpu->kvm, __gpa, &__x, sizeof(__x)); \
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})
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/**
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* write_guest_lc - copy data from kernel space to guest vcpu's lowcore
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* @vcpu: virtual cpu
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* @gra: vcpu's source guest real address
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* @data: source address in kernel space
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* @len: number of bytes to copy
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*
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* Copy data from kernel space to guest vcpu's lowcore. The entire range must
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* be located within the vcpu's lowcore, otherwise the result is undefined.
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*
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* Returns zero on success or -EFAULT on error.
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*
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* Note: an error indicates that either the kernel is out of memory or
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* the guest memory mapping is broken. In any case the best solution
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* would be to terminate the guest.
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* It is wrong to inject a guest exception.
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*/
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static inline __must_check
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int write_guest_lc(struct kvm_vcpu *vcpu, unsigned long gra, void *data,
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unsigned long len)
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{
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unsigned long gpa = gra + kvm_s390_get_prefix(vcpu);
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return kvm_write_guest(vcpu->kvm, gpa, data, len);
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}
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/**
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* read_guest_lc - copy data from guest vcpu's lowcore to kernel space
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* @vcpu: virtual cpu
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* @gra: vcpu's source guest real address
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* @data: destination address in kernel space
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* @len: number of bytes to copy
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*
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* Copy data from guest vcpu's lowcore to kernel space. The entire range must
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* be located within the vcpu's lowcore, otherwise the result is undefined.
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*
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* Returns zero on success or -EFAULT on error.
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*
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* Note: an error indicates that either the kernel is out of memory or
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* the guest memory mapping is broken. In any case the best solution
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* would be to terminate the guest.
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* It is wrong to inject a guest exception.
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*/
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static inline __must_check
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int read_guest_lc(struct kvm_vcpu *vcpu, unsigned long gra, void *data,
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unsigned long len)
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{
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unsigned long gpa = gra + kvm_s390_get_prefix(vcpu);
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return kvm_read_guest(vcpu->kvm, gpa, data, len);
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}
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int guest_translate_address(struct kvm_vcpu *vcpu, unsigned long gva,
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ar_t ar, unsigned long *gpa, int write);
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int check_gva_range(struct kvm_vcpu *vcpu, unsigned long gva, ar_t ar,
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unsigned long length, int is_write);
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int access_guest(struct kvm_vcpu *vcpu, unsigned long ga, ar_t ar, void *data,
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unsigned long len, int write);
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int access_guest_real(struct kvm_vcpu *vcpu, unsigned long gra,
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void *data, unsigned long len, int write);
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/**
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* write_guest - copy data from kernel space to guest space
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* @vcpu: virtual cpu
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* @ga: guest address
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* @ar: access register
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* @data: source address in kernel space
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* @len: number of bytes to copy
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*
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* Copy @len bytes from @data (kernel space) to @ga (guest address).
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* In order to copy data to guest space the PSW of the vcpu is inspected:
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* If DAT is off data will be copied to guest real or absolute memory.
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* If DAT is on data will be copied to the address space as specified by
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* the address space bits of the PSW:
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* Primary, secondary, home space or access register mode.
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* The addressing mode of the PSW is also inspected, so that address wrap
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* around is taken into account for 24-, 31- and 64-bit addressing mode,
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* if the to be copied data crosses page boundaries in guest address space.
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* In addition also low address and DAT protection are inspected before
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* copying any data (key protection is currently not implemented).
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*
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* This function modifies the 'struct kvm_s390_pgm_info pgm' member of @vcpu.
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* In case of an access exception (e.g. protection exception) pgm will contain
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* all data necessary so that a subsequent call to 'kvm_s390_inject_prog_vcpu()'
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* will inject a correct exception into the guest.
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* If no access exception happened, the contents of pgm are undefined when
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* this function returns.
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*
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* Returns: - zero on success
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* - a negative value if e.g. the guest mapping is broken or in
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* case of out-of-memory. In this case the contents of pgm are
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* undefined. Also parts of @data may have been copied to guest
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* space.
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* - a positive value if an access exception happened. In this case
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* the returned value is the program interruption code and the
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* contents of pgm may be used to inject an exception into the
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* guest. No data has been copied to guest space.
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*
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* Note: in case an access exception is recognized no data has been copied to
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* guest space (this is also true, if the to be copied data would cross
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* one or more page boundaries in guest space).
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* Therefore this function may be used for nullifying and suppressing
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* instruction emulation.
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* It may also be used for terminating instructions, if it is undefined
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* if data has been changed in guest space in case of an exception.
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*/
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static inline __must_check
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int write_guest(struct kvm_vcpu *vcpu, unsigned long ga, ar_t ar, void *data,
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unsigned long len)
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{
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return access_guest(vcpu, ga, ar, data, len, 1);
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}
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/**
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* read_guest - copy data from guest space to kernel space
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* @vcpu: virtual cpu
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* @ga: guest address
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* @ar: access register
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* @data: destination address in kernel space
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* @len: number of bytes to copy
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*
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* Copy @len bytes from @ga (guest address) to @data (kernel space).
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*
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* The behaviour of read_guest is identical to write_guest, except that
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* data will be copied from guest space to kernel space.
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*/
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static inline __must_check
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int read_guest(struct kvm_vcpu *vcpu, unsigned long ga, ar_t ar, void *data,
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unsigned long len)
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{
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return access_guest(vcpu, ga, ar, data, len, 0);
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}
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/**
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* write_guest_abs - copy data from kernel space to guest space absolute
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* @vcpu: virtual cpu
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* @gpa: guest physical (absolute) address
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* @data: source address in kernel space
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* @len: number of bytes to copy
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*
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* Copy @len bytes from @data (kernel space) to @gpa (guest absolute address).
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* It is up to the caller to ensure that the entire guest memory range is
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* valid memory before calling this function.
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* Guest low address and key protection are not checked.
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*
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* Returns zero on success or -EFAULT on error.
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*
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* If an error occurs data may have been copied partially to guest memory.
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*/
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static inline __must_check
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int write_guest_abs(struct kvm_vcpu *vcpu, unsigned long gpa, void *data,
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unsigned long len)
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{
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return kvm_write_guest(vcpu->kvm, gpa, data, len);
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}
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/**
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* read_guest_abs - copy data from guest space absolute to kernel space
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* @vcpu: virtual cpu
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* @gpa: guest physical (absolute) address
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* @data: destination address in kernel space
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* @len: number of bytes to copy
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*
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* Copy @len bytes from @gpa (guest absolute address) to @data (kernel space).
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* It is up to the caller to ensure that the entire guest memory range is
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* valid memory before calling this function.
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* Guest key protection is not checked.
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*
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* Returns zero on success or -EFAULT on error.
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*
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* If an error occurs data may have been copied partially to kernel space.
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*/
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static inline __must_check
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int read_guest_abs(struct kvm_vcpu *vcpu, unsigned long gpa, void *data,
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unsigned long len)
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{
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return kvm_read_guest(vcpu->kvm, gpa, data, len);
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}
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/**
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* write_guest_real - copy data from kernel space to guest space real
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* @vcpu: virtual cpu
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* @gra: guest real address
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* @data: source address in kernel space
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* @len: number of bytes to copy
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*
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* Copy @len bytes from @data (kernel space) to @gra (guest real address).
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* It is up to the caller to ensure that the entire guest memory range is
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* valid memory before calling this function.
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* Guest low address and key protection are not checked.
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*
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* Returns zero on success or -EFAULT on error.
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*
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* If an error occurs data may have been copied partially to guest memory.
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*/
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static inline __must_check
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int write_guest_real(struct kvm_vcpu *vcpu, unsigned long gra, void *data,
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unsigned long len)
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{
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return access_guest_real(vcpu, gra, data, len, 1);
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}
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/**
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* read_guest_real - copy data from guest space real to kernel space
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* @vcpu: virtual cpu
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* @gra: guest real address
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* @data: destination address in kernel space
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* @len: number of bytes to copy
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*
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* Copy @len bytes from @gra (guest real address) to @data (kernel space).
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* It is up to the caller to ensure that the entire guest memory range is
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* valid memory before calling this function.
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* Guest key protection is not checked.
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*
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* Returns zero on success or -EFAULT on error.
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*
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* If an error occurs data may have been copied partially to kernel space.
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*/
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static inline __must_check
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int read_guest_real(struct kvm_vcpu *vcpu, unsigned long gra, void *data,
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unsigned long len)
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{
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return access_guest_real(vcpu, gra, data, len, 0);
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}
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void ipte_lock(struct kvm_vcpu *vcpu);
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void ipte_unlock(struct kvm_vcpu *vcpu);
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int ipte_lock_held(struct kvm_vcpu *vcpu);
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int kvm_s390_check_low_addr_prot_real(struct kvm_vcpu *vcpu, unsigned long gra);
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#endif /* __KVM_S390_GACCESS_H */
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