Remove KVM's code to initialize IA32_FEAT_CTL MSR when KVM is loaded now that the MSR is initialized during boot on all CPUs that support VMX, i.e. on all CPUs that can possibly load kvm_intel.
Note, don't WARN if IA32_FEAT_CTL is unlocked, even though the MSR is unconditionally locked by init_ia32_feat_ctl(). KVM isn't tied directly to a CPU vendor detection, whereas init_ia32_feat_ctl() is invoked if and only if the CPU vendor is recognized and known to support VMX. As a result, vmx_disabled_by_bios() may be reached without going through init_ia32_feat_ctl() and thus without locking IA32_FEAT_CTL. This quirk will be eliminated in a future patch.
Reviewed-by: Jim Mattson jmattson@google.com Signed-off-by: Sean Christopherson sean.j.christopherson@intel.com --- arch/x86/kvm/vmx/vmx.c | 48 +++++++++++++++++------------------------- 1 file changed, 19 insertions(+), 29 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index ecf3ccf71bb2..50dd8026e718 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -2207,24 +2207,26 @@ static __init int vmx_disabled_by_bios(void) u64 msr;
rdmsrl(MSR_IA32_FEAT_CTL, msr); - if (msr & FEAT_CTL_LOCKED) { - /* launched w/ TXT and VMX disabled */ - if (!(msr & FEAT_CTL_VMX_ENABLED_INSIDE_SMX) - && tboot_enabled()) - return 1; - /* launched w/o TXT and VMX only enabled w/ TXT */ - if (!(msr & FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX) - && (msr & FEAT_CTL_VMX_ENABLED_INSIDE_SMX) - && !tboot_enabled()) { - printk(KERN_WARNING "kvm: disable TXT in the BIOS or " - "activate TXT before enabling KVM\n"); - return 1; - } - /* launched w/o TXT and VMX disabled */ - if (!(msr & FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX) - && !tboot_enabled()) - return 1; + + if (unlikely(!(msr & FEAT_CTL_LOCKED))) + return 1; + + /* launched w/ TXT and VMX disabled */ + if (!(msr & FEAT_CTL_VMX_ENABLED_INSIDE_SMX) && + tboot_enabled()) + return 1; + /* launched w/o TXT and VMX only enabled w/ TXT */ + if (!(msr & FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX) && + (msr & FEAT_CTL_VMX_ENABLED_INSIDE_SMX) && + !tboot_enabled()) { + pr_warn("kvm: disable TXT in the BIOS or " + "activate TXT before enabling KVM\n"); + return 1; } + /* launched w/o TXT and VMX disabled */ + if (!(msr & FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX) && + !tboot_enabled()) + return 1;
return 0; } @@ -2241,7 +2243,6 @@ static int hardware_enable(void) { int cpu = raw_smp_processor_id(); u64 phys_addr = __pa(per_cpu(vmxarea, cpu)); - u64 old, test_bits;
if (cr4_read_shadow() & X86_CR4_VMXE) return -EBUSY; @@ -2269,17 +2270,6 @@ static int hardware_enable(void) */ crash_enable_local_vmclear(cpu);
- rdmsrl(MSR_IA32_FEAT_CTL, old); - - test_bits = FEAT_CTL_LOCKED; - test_bits |= FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX; - if (tboot_enabled()) - test_bits |= FEAT_CTL_VMX_ENABLED_INSIDE_SMX; - - if ((old & test_bits) != test_bits) { - /* enable and lock */ - wrmsrl(MSR_IA32_FEAT_CTL, old | test_bits); - } kvm_cpu_vmxon(phys_addr); if (enable_ept) ept_sync_global();