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KVM: x86 emulator: fix writes to registers with modrm encodings 

A register destination encoded with a mod=3 encoding left dst.ptr NULL.
Normally we don't trap writes to registers, but in the case of smsw, we do.

Fix by pointing dst.ptr at the destination register.

Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Avi Kivity 2008-05-05 14:58:26 +03:00
parent f26a398891
commit 107d6d2efa
2 changed files with 6 additions and 2 deletions
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7
arch/x86/kvm/x86_emulate.c
View File

@ -677,8 +677,9 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
c->use_modrm_ea = 1;
if (c->modrm_mod == 3) {
c->modrm_val = *(unsigned long *)
decode_register(c->modrm_rm, c->regs, c->d & ByteOp);
c->modrm_ptr = decode_register(c->modrm_rm,
c->regs, c->d & ByteOp);
c->modrm_val = *(unsigned long *)c->modrm_ptr;
return rc;
}
@ -1005,6 +1006,7 @@ done_prefixes:
if ((c->d & ModRM) && c->modrm_mod == 3) {
c->src.type = OP_REG;
c->src.val = c->modrm_val;
c->src.ptr = c->modrm_ptr;
break;
}
c->src.type = OP_MEM;
@ -1049,6 +1051,7 @@ done_prefixes:
if ((c->d & ModRM) && c->modrm_mod == 3) {
c->dst.type = OP_REG;
c->dst.val = c->dst.orig_val = c->modrm_val;
c->dst.ptr = c->modrm_ptr;
break;
}
c->dst.type = OP_MEM;

1
include/asm-x86/kvm_x86_emulate.h
View File

@ -135,6 +135,7 @@ struct decode_cache {
u8 modrm_rm;
u8 use_modrm_ea;
unsigned long modrm_ea;
void *modrm_ptr;
unsigned long modrm_val;
struct fetch_cache fetch;
};