x86/vmx: Drop spec_ctrl load in VMEntry path

[PATCH] x86/vmx: Drop spec_ctrl load in VMEntry path

Andrew Cooper posted 1 patch 2 years, 3 months ago

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git fetch https://gitlab.com/xen-project/patchew/xen tags/patchew/20220201134117.13612-1-andrew.cooper3@citrix.com

xen/arch/x86/hvm/vmx/entry.S | 3 ---
1 file changed, 3 deletions(-)

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[PATCH] x86/vmx: Drop spec_ctrl load in VMEntry path

Posted by Andrew Cooper 2 years, 3 months ago

This is not needed now that the VMEntry path is not responsible for loading
the guest's MSR_SPEC_CTRL value.

Fixes: 81f0eaadf84d ("x86/spec-ctrl: Fix NMI race condition with VT-x MSR_SPEC_CTRL handling")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Roger Pau Monné <roger.pau@citrix.com>
CC: Wei Liu <wl@xen.org>
CC: Jun Nakajima <jun.nakajima@intel.com>
CC: Kevin Tian <kevin.tian@intel.com>
---
 xen/arch/x86/hvm/vmx/entry.S | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/entry.S b/xen/arch/x86/hvm/vmx/entry.S
index 7ee3382fd0ab..49651f3c435a 100644
--- a/xen/arch/x86/hvm/vmx/entry.S
+++ b/xen/arch/x86/hvm/vmx/entry.S
@@ -85,9 +85,6 @@ UNLIKELY_END(realmode)
         test %al, %al
         jz .Lvmx_vmentry_restart
 
-        mov VCPU_arch_msrs(%rbx), %rax
-        mov VCPUMSR_spec_ctrl_raw(%rax), %eax
-
         /* WARNING! `ret`, `call *`, `jmp *` not safe beyond this point. */
         /* SPEC_CTRL_EXIT_TO_VMX   Req: %rsp=regs/cpuinfo              Clob:    */
         ALTERNATIVE "", __stringify(verw CPUINFO_verw_sel(%rsp)), X86_FEATURE_SC_VERW_HVM
-- 
2.11.0

Re: [PATCH] x86/vmx: Drop spec_ctrl load in VMEntry path

Posted by Jan Beulich 2 years, 3 months ago

On 01.02.2022 14:41, Andrew Cooper wrote:
> This is not needed now that the VMEntry path is not responsible for loading
> the guest's MSR_SPEC_CTRL value.
> 
> Fixes: 81f0eaadf84d ("x86/spec-ctrl: Fix NMI race condition with VT-x MSR_SPEC_CTRL handling")
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

Reviewed-by: Jan Beulich <jbeulich@suse.com>