Commit d95fb12f authored by Heiko Carstens's avatar Heiko Carstens Committed by Christian Borntraeger

KVM: s390: add lowcore access functions

put_guest_lc, read_guest_lc and write_guest_lc are guest access
functions which shall only be used to access the lowcore of a vcpu.
These functions should be used for e.g. interrupt handlers where no
guest memory access protection facilities, like key or low address
protection, are applicable.

At a later point guest vcpu lowcore access should happen via pinned
prefix pages, so that these pages can be accessed directly via the
kernel mapping. All of these *_lc functions can be removed then.
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: default avatarThomas Huth <thuth@linux.vnet.ibm.com>
Reviewed-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
parent 1b0462e5
/*
* access guest memory
*
* Copyright IBM Corp. 2008, 2009
* Copyright IBM Corp. 2008, 2014
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License (version 2 only)
......@@ -15,7 +15,8 @@
#include <linux/compiler.h>
#include <linux/kvm_host.h>
#include <asm/uaccess.h>
#include <linux/uaccess.h>
#include <linux/ptrace.h>
#include "kvm-s390.h"
/* Convert real to absolute address by applying the prefix of the CPU */
......@@ -136,4 +137,94 @@ static inline int __copy_guest(struct kvm_vcpu *vcpu, unsigned long to,
#define copy_from_guest_absolute(vcpu, to, from, size) \
__copy_guest(vcpu, (unsigned long)to, from, size, 0, 0)
/*
* put_guest_lc, read_guest_lc and write_guest_lc are guest access functions
* which shall only be used to access the lowcore of a vcpu.
* These functions should be used for e.g. interrupt handlers where no
* guest memory access protection facilities, like key or low address
* protection, are applicable.
* At a later point guest vcpu lowcore access should happen via pinned
* prefix pages, so that these pages can be accessed directly via the
* kernel mapping. All of these *_lc functions can be removed then.
*/
/**
* put_guest_lc - write a simple variable to a guest vcpu's lowcore
* @vcpu: virtual cpu
* @x: value to copy to guest
* @gra: vcpu's destination guest real address
*
* Copies a simple value from kernel space to a guest vcpu's lowcore.
* The size of the variable may be 1, 2, 4 or 8 bytes. The destination
* must be located in the vcpu's lowcore. Otherwise the result is undefined.
*
* Returns zero on success or -EFAULT on error.
*
* Note: an error indicates that either the kernel is out of memory or
* the guest memory mapping is broken. In any case the best solution
* would be to terminate the guest.
* It is wrong to inject a guest exception.
*/
#define put_guest_lc(vcpu, x, gra) \
({ \
struct kvm_vcpu *__vcpu = (vcpu); \
__typeof__(*(gra)) __x = (x); \
unsigned long __gpa; \
\
__gpa = (unsigned long)(gra); \
__gpa += __vcpu->arch.sie_block->prefix; \
kvm_write_guest(__vcpu->kvm, __gpa, &__x, sizeof(__x)); \
})
/**
* write_guest_lc - copy data from kernel space to guest vcpu's lowcore
* @vcpu: virtual cpu
* @gra: vcpu's source guest real address
* @data: source address in kernel space
* @len: number of bytes to copy
*
* Copy data from kernel space to guest vcpu's lowcore. The entire range must
* be located within the vcpu's lowcore, otherwise the result is undefined.
*
* Returns zero on success or -EFAULT on error.
*
* Note: an error indicates that either the kernel is out of memory or
* the guest memory mapping is broken. In any case the best solution
* would be to terminate the guest.
* It is wrong to inject a guest exception.
*/
static inline __must_check
int write_guest_lc(struct kvm_vcpu *vcpu, unsigned long gra, void *data,
unsigned long len)
{
unsigned long gpa = gra + vcpu->arch.sie_block->prefix;
return kvm_write_guest(vcpu->kvm, gpa, data, len);
}
/**
* read_guest_lc - copy data from guest vcpu's lowcore to kernel space
* @vcpu: virtual cpu
* @gra: vcpu's source guest real address
* @data: destination address in kernel space
* @len: number of bytes to copy
*
* Copy data from guest vcpu's lowcore to kernel space. The entire range must
* be located within the vcpu's lowcore, otherwise the result is undefined.
*
* Returns zero on success or -EFAULT on error.
*
* Note: an error indicates that either the kernel is out of memory or
* the guest memory mapping is broken. In any case the best solution
* would be to terminate the guest.
* It is wrong to inject a guest exception.
*/
static inline __must_check
int read_guest_lc(struct kvm_vcpu *vcpu, unsigned long gra, void *data,
unsigned long len)
{
unsigned long gpa = gra + vcpu->arch.sie_block->prefix;
return kvm_read_guest(vcpu->kvm, gpa, data, len);
}
#endif /* __KVM_S390_GACCESS_H */
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