Commit a807b78a authored by Emanuele Giuseppe Esposito's avatar Emanuele Giuseppe Esposito Committed by Paolo Bonzini
Browse files

kvm: vmx: Add IA32_FLUSH_CMD guest support 



Expose IA32_FLUSH_CMD to the guest if the guest CPUID enumerates
support for this MSR. As with IA32_PRED_CMD, permission for
unintercepted writes to this MSR will be granted to the guest after
the first non-zero write.

Co-developed-by: default avatarJim Mattson <jmattson@google.com>
Signed-off-by: default avatarJim Mattson <jmattson@google.com>
Signed-off-by: default avatarEmanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20230201132905.549148-2-eesposit@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent fbc722aa

arch/x86/kvm/vmx/nested.c

+3 −0
Original line number Diff line number Diff line
@@ -654,6 +654,9 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu, 
	nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,

					 MSR_IA32_PRED_CMD, MSR_TYPE_W);



	nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,

					 MSR_IA32_FLUSH_CMD, MSR_TYPE_W);



	kvm_vcpu_unmap(vcpu, &vmx->nested.msr_bitmap_map, false);



	vmx->nested.force_msr_bitmap_recalc = false;

arch/x86/kvm/vmx/vmx.c

+43 −25
Original line number Diff line number Diff line
@@ -2133,6 +2133,39 @@ static u64 vmx_get_supported_debugctl(struct kvm_vcpu *vcpu, bool host_initiated 
	return debugctl;

}



static int vmx_set_msr_ia32_cmd(struct kvm_vcpu *vcpu,

				struct msr_data *msr_info,

				bool guest_has_feat, u64 cmd,

				int x86_feature_bit)

{

	if (!msr_info->host_initiated && !guest_has_feat)

		return 1;



	if (!(msr_info->data & ~cmd))

		return 1;

	if (!boot_cpu_has(x86_feature_bit))

		return 1;

	if (!msr_info->data)

		return 0;



	wrmsrl(msr_info->index, cmd);



	/*

	 * For non-nested:

	 * When it's written (to non-zero) for the first time, pass

	 * it through.

	 *

	 * For nested:

	 * The handling of the MSR bitmap for L2 guests is done in

	 * nested_vmx_prepare_msr_bitmap. We should not touch the

	 * vmcs02.msr_bitmap here since it gets completely overwritten

	 * in the merging.

	 */

	vmx_disable_intercept_for_msr(vcpu, msr_info->index, MSR_TYPE_W);



	return 0;

}



/*

 * Writes msr value into the appropriate "register".

 * Returns 0 on success, non-0 otherwise.
@@ -2286,31 +2319,16 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 
			return 1;

		goto find_uret_msr;

	case MSR_IA32_PRED_CMD:

		if (!msr_info->host_initiated &&

		    !guest_has_pred_cmd_msr(vcpu))

			return 1;



		if (data & ~PRED_CMD_IBPB)

			return 1;

		if (!boot_cpu_has(X86_FEATURE_IBPB))

			return 1;

		if (!data)

		ret = vmx_set_msr_ia32_cmd(vcpu, msr_info,

					   guest_has_pred_cmd_msr(vcpu),

					   PRED_CMD_IBPB,

					   X86_FEATURE_IBPB);

		break;



		wrmsrl(MSR_IA32_PRED_CMD, PRED_CMD_IBPB);



		/*

		 * For non-nested:

		 * When it's written (to non-zero) for the first time, pass

		 * it through.

		 *

		 * For nested:

		 * The handling of the MSR bitmap for L2 guests is done in

		 * nested_vmx_prepare_msr_bitmap. We should not touch the

		 * vmcs02.msr_bitmap here since it gets completely overwritten

		 * in the merging.

		 */

		vmx_disable_intercept_for_msr(vcpu, MSR_IA32_PRED_CMD, MSR_TYPE_W);

	case MSR_IA32_FLUSH_CMD:

		ret = vmx_set_msr_ia32_cmd(vcpu, msr_info,

					   guest_cpuid_has(vcpu, X86_FEATURE_FLUSH_L1D),

					   L1D_FLUSH,

					   X86_FEATURE_FLUSH_L1D);

		break;

	case MSR_IA32_CR_PAT:

		if (!kvm_pat_valid(data))