From dfa625e15f3d6c374637f2bb789e1f444c2781c3 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Fri, 22 Aug 2014 14:29:37 +0200 Subject: [PATCH] VMX: fix DebugCtl MSR clearing The previous shortcut was wrong, as it bypassed the necessary vmwrite: All we really want to avoid if the guest writes zero is to add the MSR to the host-load list. Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper Acked-by: Kevin Tian --- xen/arch/x86/hvm/vmx/vmx.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c index fb65c7d512..46eeee2ce7 100644 --- a/xen/arch/x86/hvm/vmx/vmx.c +++ b/xen/arch/x86/hvm/vmx/vmx.c @@ -2246,8 +2246,6 @@ static int vmx_msr_write_intercept(unsigned int msr, uint64_t msr_content) int i, rc = 0; uint64_t supported = IA32_DEBUGCTLMSR_LBR | IA32_DEBUGCTLMSR_BTF; - if ( !msr_content ) - break; if ( msr_content & ~supported ) { /* Perhaps some other bits are supported in vpmu. */ @@ -2267,12 +2265,10 @@ static int vmx_msr_write_intercept(unsigned int msr, uint64_t msr_content) } if ( (rc < 0) || - (vmx_add_host_load_msr(msr) < 0) ) + (msr_content && (vmx_add_host_load_msr(msr) < 0)) ) hvm_inject_hw_exception(TRAP_machine_check, 0); else - { __vmwrite(GUEST_IA32_DEBUGCTL, msr_content); - } break; } -- 2.30.2