From bd201eb1681ce6eb1b2d53b4d26a27081956770f Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Wed, 14 Dec 2016 10:10:39 +0100 Subject: [PATCH] x86emul: check for LAHF_LM availability We can't exclude someone wanting to hide LAHF/SAHF from 64-bit guests. Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper --- xen/arch/x86/x86_emulate/x86_emulate.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c index 43a6794a07..2c23e473db 100644 --- a/xen/arch/x86/x86_emulate/x86_emulate.c +++ b/xen/arch/x86/x86_emulate/x86_emulate.c @@ -1299,6 +1299,7 @@ static bool vcpu_has( #define vcpu_has_sse4_2() vcpu_has( 1, ECX, 20, ctxt, ops) #define vcpu_has_movbe() vcpu_has( 1, ECX, 22, ctxt, ops) #define vcpu_has_avx() vcpu_has( 1, ECX, 28, ctxt, ops) +#define vcpu_has_lahf_lm() vcpu_has(0x80000001, ECX, 0, ctxt, ops) #define vcpu_has_lzcnt() vcpu_has(0x80000001, ECX, 5, ctxt, ops) #define vcpu_has_misalignsse() vcpu_has(0x80000001, ECX, 7, ctxt, ops) #define vcpu_has_bmi1() vcpu_has( 7, EBX, 3, ctxt, ops) @@ -3234,11 +3235,15 @@ x86_emulate( } case 0x9e: /* sahf */ + if ( mode_64bit() ) + vcpu_must_have(lahf_lm); *(uint8_t *)&_regs.eflags = (((uint8_t *)&_regs.eax)[1] & EFLAGS_MASK) | EFLG_MBS; break; case 0x9f: /* lahf */ + if ( mode_64bit() ) + vcpu_must_have(lahf_lm); ((uint8_t *)&_regs.eax)[1] = (_regs.eflags & EFLAGS_MASK) | EFLG_MBS; break; -- 2.30.2