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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: Heiko Carstens <heiko.carstens@de.ibm.com> Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
Heiko Carstens
Christian Borntraeger
parent
1b0462e574
commit
d95fb12ff4
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@ -1,7 +1,7 @@
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/*
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* access guest memory
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*
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* Copyright IBM Corp. 2008, 2009
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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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@ -15,7 +15,8 @@
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#include <linux/compiler.h>
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#include <linux/kvm_host.h>
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#include <asm/uaccess.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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/* Convert real to absolute address by applying the prefix of the CPU */
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@ -136,4 +137,94 @@ static inline int __copy_guest(struct kvm_vcpu *vcpu, unsigned long to,
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#define copy_from_guest_absolute(vcpu, to, from, size) \
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__copy_guest(vcpu, (unsigned long)to, from, size, 0, 0)
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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 += __vcpu->arch.sie_block->prefix; \
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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 + vcpu->arch.sie_block->prefix;
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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 + vcpu->arch.sie_block->prefix;
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return kvm_read_guest(vcpu->kvm, gpa, data, len);
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}
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#endif /* __KVM_S390_GACCESS_H */
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