A guest may not be configured to support RDRAND, even when the host
does. If the guest does not support RDRAND, intercept the instruction
and synthesize #UD. Also clear the "allowed-1" bit for RDRAND exiting
in the IA32_VMX_PROCBASED_CTLS2 MSR.
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
arch/x86/kvm/vmx.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 8346fd53a42f..b13370381988 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3661,6 +3661,7 @@ static __init int setup_vmcs_config(struct vmcs_config
*vmcs_conf)
SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
SECONDARY_EXEC_SHADOW_VMCS |
SECONDARY_EXEC_XSAVES |
+ SECONDARY_EXEC_RDRAND |
SECONDARY_EXEC_RDSEED |
SECONDARY_EXEC_ENABLE_PML |
SECONDARY_EXEC_TSC_SCALING |
@@ -5295,6 +5296,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx
*vmx)
if (!enable_pml)
exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
+ if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDRAND))
+ exec_control &= ~SECONDARY_EXEC_RDRAND;
+
if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDSEED))
exec_control &= ~SECONDARY_EXEC_RDSEED;
@@ -8051,6 +8055,7 @@ static int (*const kvm_vmx_exit_handlers[])(struct
kvm_vcpu *vcpu) = {
[EXIT_REASON_MONITOR_INSTRUCTION] = handle_monitor,
[EXIT_REASON_INVEPT] = handle_invept,
[EXIT_REASON_INVVPID] = handle_invvpid,
+ [EXIT_REASON_RDRAND] = handle_invalid_op,
[EXIT_REASON_RDSEED] = handle_invalid_op,
[EXIT_REASON_XSAVES] = handle_xsaves,
[EXIT_REASON_XRSTORS] = handle_xrstors,
@@ -8980,6 +8985,12 @@ static bool vmx_mpx_supported(void)
(vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_BNDCFGS);
}
+static bool vmx_rdrand_supported(void)
+{
+ return vmcs_config.cpu_based_2nd_exec_ctrl &
+ SECONDARY_EXEC_RDRAND;
+}
+
static bool vmx_rdseed_supported(void)
{
return vmcs_config.cpu_based_2nd_exec_ctrl &
@@ -9735,6 +9746,24 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
}
}
+ if (vmx_rdrand_supported()) {
+ bool rdrand_enabled = guest_cpuid_has(vcpu, X86_FEATURE_RDRAND);
+
+ if (rdrand_enabled)
+ secondary_exec_ctl &= ~SECONDARY_EXEC_RDRAND;
+ else
+ secondary_exec_ctl |= SECONDARY_EXEC_RDRAND;
+
+ if (nested) {
+ if (rdrand_enabled)
+ vmx->nested.nested_vmx_secondary_ctls_high |=
+ SECONDARY_EXEC_RDRAND;
+ else
+ vmx->nested.nested_vmx_secondary_ctls_high &=
+ ~SECONDARY_EXEC_RDRAND;
+ }
+ }
+
if (vmx_rdseed_supported()) {
bool rdseed_enabled = guest_cpuid_has(vcpu, X86_FEATURE_RDSEED);
--
1.8.3.1
