@@ -2236,18 +2236,33 @@ static __init int vmx_disabled_by_bios(void)
!boot_cpu_has(X86_FEATURE_VMX);
}
-static void kvm_cpu_vmxon(u64 addr)
+static int kvm_cpu_vmxon(u64 vmxon_pointer)
{
+ u64 msr;
+
cr4_set_bits(X86_CR4_VMXE);
intel_pt_handle_vmx(1);
- asm volatile ("vmxon %0" : : "m"(addr));
+ asm_volatile_goto("1: vmxon %[vmxon_pointer]\n\t"
+ _ASM_EXTABLE(1b, %l[fault])
+ : : [vmxon_pointer] "m"(vmxon_pointer)
+ : : fault);
+ return 0;
+
+fault:
+ WARN_ONCE(1, "VMXON faulted, MSR_IA32_FEAT_CTL (0x3a) = 0x%llx\n",
+ rdmsrl_safe(MSR_IA32_FEAT_CTL, &msr) ? 0xdeadbeef : msr);
+ intel_pt_handle_vmx(0);
+ cr4_clear_bits(X86_CR4_VMXE);
+
+ return -EFAULT;
}
static int hardware_enable(void)
{
int cpu = raw_smp_processor_id();
u64 phys_addr = __pa(per_cpu(vmxarea, cpu));
+ int r;
if (cr4_read_shadow() & X86_CR4_VMXE)
return -EBUSY;
@@ -2264,7 +2279,10 @@ static int hardware_enable(void)
INIT_LIST_HEAD(&per_cpu(blocked_vcpu_on_cpu, cpu));
spin_lock_init(&per_cpu(blocked_vcpu_on_cpu_lock, cpu));
- kvm_cpu_vmxon(phys_addr);
+ r = kvm_cpu_vmxon(phys_addr);
+ if (r)
+ return r;
+
if (enable_ept)
ept_sync_global();
Gracefully handle faults on VMXON, e.g. #GP due to VMX being disabled by BIOS, instead of letting the fault crash the system. Now that KVM uses cpufeatures to query support instead of reading MSR_IA32_FEAT_CTL directly, it's possible for a bug in a different subsystem to cause KVM to incorrectly attempt VMXON[*]. Crashing the system is especially annoying if the system is configured such that hardware_enable() will be triggered during boot. Oppurtunistically rename @addr to @vmxon_pointer and use a named param to reference it in the inline assembly. Print 0xdeadbeef in the ultra-"rare" case that reading MSR_IA32_FEAT_CTL also faults. [*] https://lkml.kernel.org/r/20200226231615.13664-1-sean.j.christopherson@intel.com Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> --- arch/x86/kvm/vmx/vmx.c | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-)