From d95fb12ff4d73e897126043bb5d03a068997a2ef Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Wed, 1 Jan 2014 16:23:29 +0100 Subject: [PATCH] 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 Reviewed-by: Thomas Huth Reviewed-by: Cornelia Huck Signed-off-by: Christian Borntraeger --- arch/s390/kvm/gaccess.h | 95 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 93 insertions(+), 2 deletions(-) diff --git a/arch/s390/kvm/gaccess.h b/arch/s390/kvm/gaccess.h index ae3cb638f220..917aeaa04fff 100644 --- a/arch/s390/kvm/gaccess.h +++ b/arch/s390/kvm/gaccess.h @@ -1,7 +1,7 @@ /* * 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 #include -#include +#include +#include #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 */ -- 2.20.1