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744b37fb5a
Guest access functions like copy_to/from_guest() call __guestaddr_to_user() which in turn call gmap_fault() in order to translate a guest address to a user space address. In error case __guest_addr_to_user() returns either -EFAULT or -ENOMEM. The copy_to/from_guest functions just pass these return values down to the callers. The -ENOMEM case however is problematic since there are several places which access guest memory like: rc = copy_to_guest(...); if (rc == -EFAULT) error_handling(); So in case of -ENOMEM the code assumes that the guest memory access succeeded even though it failed. This can cause guest data or state corruption. If __guestaddr_to_user() returns -ENOMEM the meaning is that a valid user space mapping exists, but there was not enough memory available when trying to build the guest mapping. In other words an out-of-memory situation occured. For normal user space accesses an out-of-memory situation causes the page fault handler to map -ENOMEM to -EFAULT (see fixup code in do_no_context()). We need to do exactly the same for the kvm gaccess functions. So __guestaddr_to_user() should just map all error codes to -EFAULT. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
390 lines
8.6 KiB
C
390 lines
8.6 KiB
C
/*
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* access guest memory
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*
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* Copyright IBM Corp. 2008, 2009
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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 <asm/uaccess.h>
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#include "kvm-s390.h"
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static inline void __user *__guestaddr_to_user(struct kvm_vcpu *vcpu,
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unsigned long guestaddr)
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{
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unsigned long prefix = vcpu->arch.sie_block->prefix;
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unsigned long uaddress;
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if (guestaddr < 2 * PAGE_SIZE)
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guestaddr += prefix;
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else if ((guestaddr >= prefix) && (guestaddr < prefix + 2 * PAGE_SIZE))
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guestaddr -= prefix;
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uaddress = gmap_fault(guestaddr, vcpu->arch.gmap);
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if (IS_ERR_VALUE(uaddress))
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uaddress = -EFAULT;
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return (void __user *)uaddress;
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}
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static inline int get_guest_u64(struct kvm_vcpu *vcpu, unsigned long guestaddr,
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u64 *result)
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{
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void __user *uptr = __guestaddr_to_user(vcpu, guestaddr);
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BUG_ON(guestaddr & 7);
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if (IS_ERR((void __force *) uptr))
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return PTR_ERR((void __force *) uptr);
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return get_user(*result, (unsigned long __user *) uptr);
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}
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static inline int get_guest_u32(struct kvm_vcpu *vcpu, unsigned long guestaddr,
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u32 *result)
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{
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void __user *uptr = __guestaddr_to_user(vcpu, guestaddr);
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BUG_ON(guestaddr & 3);
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if (IS_ERR((void __force *) uptr))
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return PTR_ERR((void __force *) uptr);
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return get_user(*result, (u32 __user *) uptr);
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}
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static inline int get_guest_u16(struct kvm_vcpu *vcpu, unsigned long guestaddr,
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u16 *result)
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{
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void __user *uptr = __guestaddr_to_user(vcpu, guestaddr);
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BUG_ON(guestaddr & 1);
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if (IS_ERR(uptr))
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return PTR_ERR(uptr);
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return get_user(*result, (u16 __user *) uptr);
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}
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static inline int get_guest_u8(struct kvm_vcpu *vcpu, unsigned long guestaddr,
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u8 *result)
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{
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void __user *uptr = __guestaddr_to_user(vcpu, guestaddr);
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if (IS_ERR((void __force *) uptr))
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return PTR_ERR((void __force *) uptr);
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return get_user(*result, (u8 __user *) uptr);
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}
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static inline int put_guest_u64(struct kvm_vcpu *vcpu, unsigned long guestaddr,
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u64 value)
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{
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void __user *uptr = __guestaddr_to_user(vcpu, guestaddr);
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BUG_ON(guestaddr & 7);
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if (IS_ERR((void __force *) uptr))
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return PTR_ERR((void __force *) uptr);
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return put_user(value, (u64 __user *) uptr);
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}
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static inline int put_guest_u32(struct kvm_vcpu *vcpu, unsigned long guestaddr,
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u32 value)
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{
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void __user *uptr = __guestaddr_to_user(vcpu, guestaddr);
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BUG_ON(guestaddr & 3);
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if (IS_ERR((void __force *) uptr))
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return PTR_ERR((void __force *) uptr);
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return put_user(value, (u32 __user *) uptr);
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}
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static inline int put_guest_u16(struct kvm_vcpu *vcpu, unsigned long guestaddr,
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u16 value)
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{
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void __user *uptr = __guestaddr_to_user(vcpu, guestaddr);
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BUG_ON(guestaddr & 1);
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if (IS_ERR((void __force *) uptr))
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return PTR_ERR((void __force *) uptr);
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return put_user(value, (u16 __user *) uptr);
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}
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static inline int put_guest_u8(struct kvm_vcpu *vcpu, unsigned long guestaddr,
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u8 value)
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{
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void __user *uptr = __guestaddr_to_user(vcpu, guestaddr);
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if (IS_ERR((void __force *) uptr))
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return PTR_ERR((void __force *) uptr);
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return put_user(value, (u8 __user *) uptr);
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}
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static inline int __copy_to_guest_slow(struct kvm_vcpu *vcpu,
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unsigned long guestdest,
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void *from, unsigned long n)
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{
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int rc;
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unsigned long i;
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u8 *data = from;
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for (i = 0; i < n; i++) {
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rc = put_guest_u8(vcpu, guestdest++, *(data++));
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if (rc < 0)
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return rc;
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}
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return 0;
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}
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static inline int __copy_to_guest_fast(struct kvm_vcpu *vcpu,
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unsigned long guestdest,
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void *from, unsigned long n)
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{
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int r;
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void __user *uptr;
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unsigned long size;
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if (guestdest + n < guestdest)
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return -EFAULT;
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/* simple case: all within one segment table entry? */
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if ((guestdest & PMD_MASK) == ((guestdest+n) & PMD_MASK)) {
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uptr = (void __user *) gmap_fault(guestdest, vcpu->arch.gmap);
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if (IS_ERR((void __force *) uptr))
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return PTR_ERR((void __force *) uptr);
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r = copy_to_user(uptr, from, n);
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if (r)
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r = -EFAULT;
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goto out;
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}
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/* copy first segment */
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uptr = (void __user *)gmap_fault(guestdest, vcpu->arch.gmap);
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if (IS_ERR((void __force *) uptr))
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return PTR_ERR((void __force *) uptr);
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size = PMD_SIZE - (guestdest & ~PMD_MASK);
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r = copy_to_user(uptr, from, size);
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if (r) {
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r = -EFAULT;
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goto out;
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}
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from += size;
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n -= size;
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guestdest += size;
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/* copy full segments */
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while (n >= PMD_SIZE) {
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uptr = (void __user *)gmap_fault(guestdest, vcpu->arch.gmap);
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if (IS_ERR((void __force *) uptr))
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return PTR_ERR((void __force *) uptr);
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r = copy_to_user(uptr, from, PMD_SIZE);
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if (r) {
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r = -EFAULT;
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goto out;
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}
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from += PMD_SIZE;
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n -= PMD_SIZE;
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guestdest += PMD_SIZE;
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}
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/* copy the tail segment */
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if (n) {
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uptr = (void __user *)gmap_fault(guestdest, vcpu->arch.gmap);
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if (IS_ERR((void __force *) uptr))
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return PTR_ERR((void __force *) uptr);
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r = copy_to_user(uptr, from, n);
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if (r)
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r = -EFAULT;
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}
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out:
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return r;
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}
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static inline int copy_to_guest_absolute(struct kvm_vcpu *vcpu,
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unsigned long guestdest,
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void *from, unsigned long n)
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{
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return __copy_to_guest_fast(vcpu, guestdest, from, n);
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}
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static inline int copy_to_guest(struct kvm_vcpu *vcpu, unsigned long guestdest,
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void *from, unsigned long n)
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{
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unsigned long prefix = vcpu->arch.sie_block->prefix;
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if ((guestdest < 2 * PAGE_SIZE) && (guestdest + n > 2 * PAGE_SIZE))
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goto slowpath;
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if ((guestdest < prefix) && (guestdest + n > prefix))
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goto slowpath;
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if ((guestdest < prefix + 2 * PAGE_SIZE)
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&& (guestdest + n > prefix + 2 * PAGE_SIZE))
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goto slowpath;
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if (guestdest < 2 * PAGE_SIZE)
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guestdest += prefix;
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else if ((guestdest >= prefix) && (guestdest < prefix + 2 * PAGE_SIZE))
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guestdest -= prefix;
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return __copy_to_guest_fast(vcpu, guestdest, from, n);
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slowpath:
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return __copy_to_guest_slow(vcpu, guestdest, from, n);
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}
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static inline int __copy_from_guest_slow(struct kvm_vcpu *vcpu, void *to,
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unsigned long guestsrc,
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unsigned long n)
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{
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int rc;
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unsigned long i;
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u8 *data = to;
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for (i = 0; i < n; i++) {
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rc = get_guest_u8(vcpu, guestsrc++, data++);
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if (rc < 0)
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return rc;
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}
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return 0;
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}
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static inline int __copy_from_guest_fast(struct kvm_vcpu *vcpu, void *to,
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unsigned long guestsrc,
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unsigned long n)
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{
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int r;
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void __user *uptr;
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unsigned long size;
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if (guestsrc + n < guestsrc)
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return -EFAULT;
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/* simple case: all within one segment table entry? */
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if ((guestsrc & PMD_MASK) == ((guestsrc+n) & PMD_MASK)) {
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uptr = (void __user *) gmap_fault(guestsrc, vcpu->arch.gmap);
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if (IS_ERR((void __force *) uptr))
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return PTR_ERR((void __force *) uptr);
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r = copy_from_user(to, uptr, n);
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if (r)
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r = -EFAULT;
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goto out;
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}
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/* copy first segment */
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uptr = (void __user *)gmap_fault(guestsrc, vcpu->arch.gmap);
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if (IS_ERR((void __force *) uptr))
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return PTR_ERR((void __force *) uptr);
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size = PMD_SIZE - (guestsrc & ~PMD_MASK);
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r = copy_from_user(to, uptr, size);
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if (r) {
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r = -EFAULT;
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goto out;
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}
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to += size;
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n -= size;
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guestsrc += size;
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/* copy full segments */
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while (n >= PMD_SIZE) {
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uptr = (void __user *)gmap_fault(guestsrc, vcpu->arch.gmap);
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if (IS_ERR((void __force *) uptr))
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return PTR_ERR((void __force *) uptr);
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r = copy_from_user(to, uptr, PMD_SIZE);
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if (r) {
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r = -EFAULT;
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goto out;
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}
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to += PMD_SIZE;
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n -= PMD_SIZE;
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guestsrc += PMD_SIZE;
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}
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/* copy the tail segment */
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if (n) {
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uptr = (void __user *)gmap_fault(guestsrc, vcpu->arch.gmap);
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if (IS_ERR((void __force *) uptr))
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return PTR_ERR((void __force *) uptr);
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r = copy_from_user(to, uptr, n);
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if (r)
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r = -EFAULT;
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}
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out:
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return r;
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}
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static inline int copy_from_guest_absolute(struct kvm_vcpu *vcpu, void *to,
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unsigned long guestsrc,
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unsigned long n)
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{
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return __copy_from_guest_fast(vcpu, to, guestsrc, n);
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}
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static inline int copy_from_guest(struct kvm_vcpu *vcpu, void *to,
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unsigned long guestsrc, unsigned long n)
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{
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unsigned long prefix = vcpu->arch.sie_block->prefix;
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if ((guestsrc < 2 * PAGE_SIZE) && (guestsrc + n > 2 * PAGE_SIZE))
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goto slowpath;
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if ((guestsrc < prefix) && (guestsrc + n > prefix))
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goto slowpath;
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if ((guestsrc < prefix + 2 * PAGE_SIZE)
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&& (guestsrc + n > prefix + 2 * PAGE_SIZE))
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goto slowpath;
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if (guestsrc < 2 * PAGE_SIZE)
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guestsrc += prefix;
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else if ((guestsrc >= prefix) && (guestsrc < prefix + 2 * PAGE_SIZE))
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guestsrc -= prefix;
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return __copy_from_guest_fast(vcpu, to, guestsrc, n);
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slowpath:
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return __copy_from_guest_slow(vcpu, to, guestsrc, n);
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}
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#endif
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