From ef4d3bf19855641fc8a1f621eaf06e2a2bb872bb Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 20 Dec 2019 20:45:02 -0800 Subject: [PATCH] x86/cpu: Clear VMX feature flag if VMX is not fully enabled 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 Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20191221044513.21680-9-sean.j.christopherson@intel.com --- arch/x86/kernel/cpu/feat_ctl.c | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/cpu/feat_ctl.c b/arch/x86/kernel/cpu/feat_ctl.c index c4f8f767853b42..a46c9e46f93785 100644 --- a/arch/x86/kernel/cpu/feat_ctl.c +++ b/arch/x86/kernel/cpu/feat_ctl.c @@ -5,15 +5,21 @@ #include #include +#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); + } }