On 21/08/2017 21:26, Jim Mattson wrote:
> A guest may not be configured to support RDSEED, even when the host
> does. If the guest does not support RDSEED, intercept the instruction
> and synthesize #UD. Also clear the "allowed-1" bit for RDSEED exiting
> in the IA32_VMX_PROCBASED_CTLS2 MSR.
>
> Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
Usually we're not that particular about #UD-ing on disabled instructions
(because you cannot do it for all instructions), but in this case I
agree that we should do it for the sake of getting vmexits right.
I'm applying v5 and posting shortly a similar patch for RDRAND.
Paolo
> ---
> arch/x86/kvm/vmx.c | 35 +++++++++++++++++++++++++++++++++++
> 1 file changed, 35 insertions(+)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index ed1074e98b8e..61174e1f7d0f 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -3662,6 +3662,7 @@ 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_RDSEED |
> SECONDARY_EXEC_ENABLE_PML |
> SECONDARY_EXEC_TSC_SCALING |
> SECONDARY_EXEC_ENABLE_VMFUNC;
> @@ -5298,6 +5299,9 @@ 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_RDSEED))
> + exec_control &= ~SECONDARY_EXEC_RDSEED;
> +
> return exec_control;
> }
>
> @@ -6806,6 +6810,12 @@ static int handle_mwait(struct kvm_vcpu *vcpu)
> return handle_nop(vcpu);
> }
>
> +static int handle_invalid_op(struct kvm_vcpu *vcpu)
> +{
> + kvm_queue_exception(vcpu, UD_VECTOR);
> + return 1;
> +}
> +
> static int handle_monitor_trap(struct kvm_vcpu *vcpu)
> {
> return 1;
> @@ -8050,6 +8060,7 @@ 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_RDSEED] = handle_invalid_op,
> [EXIT_REASON_XSAVES] = handle_xsaves,
> [EXIT_REASON_XRSTORS] = handle_xrstors,
> [EXIT_REASON_PML_FULL] = handle_pml_full,
> @@ -8979,6 +8990,12 @@ static bool vmx_mpx_supported(void)
> (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_BNDCFGS);
> }
>
> +static bool vmx_rdseed_supported(void)
> +{
> + return vmcs_config.cpu_based_2nd_exec_ctrl &
> + SECONDARY_EXEC_RDSEED;
> +}
> +
> static bool vmx_xsaves_supported(void)
> {
> return vmcs_config.cpu_based_2nd_exec_ctrl &
> @@ -9665,6 +9682,24 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
> }
> }
>
> + if (vmx_rdseed_supported()) {
> + bool rdseed_enabled = guest_cpuid_has(vcpu, X86_FEATURE_RDSEED);
> +
> + if (rdseed_enabled)
> + secondary_exec_ctl &= ~SECONDARY_EXEC_RDSEED;
> + else
> + secondary_exec_ctl |= SECONDARY_EXEC_RDSEED;
> +
> + if (nested) {
> + if (rdseed_enabled)
> + vmx->nested.nested_vmx_secondary_ctls_high |=
> + SECONDARY_EXEC_RDSEED;
> + else
> + vmx->nested.nested_vmx_secondary_ctls_high &=
> + ~SECONDARY_EXEC_RDSEED;
> + }
> + }
> +
> if (cpu_has_secondary_exec_ctrls())
> vmcs_set_secondary_exec_control(secondary_exec_ctl);
>
>
