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x86/cpu: Clear VMX feature flag if VMX is not fully enabled

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Now that IA32_FEAT_CTL is always configured and locked for CPUs that are
known to support VMX[*], clear the VMX capability flag if the MSR is
unsupported or BIOS disabled VMX, i.e. locked IA32_FEAT_CTL and didn't
set the appropriate VMX enable bit.

[*] Because init_ia32_feat_ctl() is called from vendors ->c_init(), it's
    still possible for IA32_FEAT_CTL to be left unlocked when VMX is
    supported by the CPU.  This is not fatal, and will be addressed in a
    future patch.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20191221044513.21680-9-sean.j.christopherson@intel.com
This commit is contained in:
Sean Christopherson 2019-12-20 20:45:02 -08:00 committed by Borislav Petkov
parent 7d37953ba8
commit ef4d3bf198
1 changed files with 20 additions and 3 deletions
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23
arch/x86/kernel/cpu/feat_ctl.c
View File

@ -5,15 +5,21 @@
#include <asm/msr-index.h>
#include <asm/processor.h>
#undef pr_fmt
#define pr_fmt(fmt) "x86/cpu: " fmt
void init_ia32_feat_ctl(struct cpuinfo_x86 *c)
{
bool tboot = tboot_enabled();
u64 msr;
if (rdmsrl_safe(MSR_IA32_FEAT_CTL, &msr))
if (rdmsrl_safe(MSR_IA32_FEAT_CTL, &msr)) {
clear_cpu_cap(c, X86_FEATURE_VMX);
return;
}
if (msr & FEAT_CTL_LOCKED)
return;
goto update_caps;
/*
* Ignore whatever value BIOS left in the MSR to avoid enabling random
@ -29,9 +35,20 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c)
if (cpu_has(c, X86_FEATURE_VMX) && IS_ENABLED(CONFIG_KVM_INTEL)) {
msr |= FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX;
if (tboot_enabled())
if (tboot)
msr |= FEAT_CTL_VMX_ENABLED_INSIDE_SMX;
}
wrmsrl(MSR_IA32_FEAT_CTL, msr);
update_caps:
if (!cpu_has(c, X86_FEATURE_VMX))
return;
if ( (tboot && !(msr & FEAT_CTL_VMX_ENABLED_INSIDE_SMX)) ||
(!tboot && !(msr & FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX))) {
pr_err_once("VMX (%s TXT) disabled by BIOS\n",
tboot ? "inside" : "outside");
clear_cpu_cap(c, X86_FEATURE_VMX);
}
}