From 0d4d9e8f55602415475e04a5dc8b4ad27845a7f9 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Tue, 18 Dec 2018 15:19:47 +0100 Subject: [PATCH] x86emul: work around SandyBridge errata There are a number of exception condition related errata on SandyBridge CPUs, some of which are unexpected #UD (others, of no interest here, are lack of mandated exceptions, or exceptions of unexpected type). Annotate the one workaround we already have, and add two more. Due to the exception recovery we have in place for stub invocations these aren't security issues. Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper --- xen/arch/x86/x86_emulate/x86_emulate.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c index 7f694fea17..d6c97651e2 100644 --- a/xen/arch/x86/x86_emulate/x86_emulate.c +++ b/xen/arch/x86/x86_emulate/x86_emulate.c @@ -6079,9 +6079,11 @@ x86_emulate( else { generate_exception_if(vex.reg != 0xf, EXC_UD); - vex.l = 0; host_and_vcpu_must_have(avx); get_fpu(X86EMUL_FPU_ymm); + + /* Work around erratum BT230. */ + vex.l = 0; } opc = init_prefixes(stub); @@ -6984,6 +6986,9 @@ x86_emulate( get_fpu(X86EMUL_FPU_mmx); } + /* Work around erratum BT36. */ + vex.w = 0; + opc = init_prefixes(stub); opc[0] = b; insn_bytes = PFX_BYTES + 1; @@ -8816,6 +8821,11 @@ x86_emulate( generate_exception_if(vex.l || vex.reg != 0xf, EXC_UD); host_and_vcpu_must_have(avx); get_fpu(X86EMUL_FPU_ymm); + + /* Work around erratum BT41. */ + if ( !mode_64bit() ) + vex.w = 0; + opc = init_prefixes(stub); goto pextr; -- 2.30.2