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Commit cae50139 authored by Jan Kiszka's avatar Jan Kiszka Committed by Paolo Bonzini
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KVM: nVMX: Clean up handling of VMX-related MSRs 



This simplifies the code and also stops issuing warning about writing to
unhandled MSRs when VMX is disabled or the Feature Control MSR is
locked - we do handle them all according to the spec.

Signed-off-by: default avatarJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 542060ea

arch/x86/include/uapi/asm/msr-index.h

+1 −0
Original line number Diff line number Diff line
@@ -527,6 +527,7 @@ 
#define MSR_IA32_VMX_TRUE_PROCBASED_CTLS 0x0000048e

#define MSR_IA32_VMX_TRUE_EXIT_CTLS      0x0000048f

#define MSR_IA32_VMX_TRUE_ENTRY_CTLS     0x00000490

#define MSR_IA32_VMX_VMFUNC             0x00000491



/* VMX_BASIC bits and bitmasks */

#define VMX_BASIC_VMCS_SIZE_SHIFT	32

arch/x86/kvm/vmx.c

+23 −56
Original line number Diff line number Diff line
@@ -2361,32 +2361,10 @@ static inline u64 vmx_control_msr(u32 low, u32 high) 
	return low | ((u64)high << 32);

}



/*

 * If we allow our guest to use VMX instructions (i.e., nested VMX), we should

 * also let it use VMX-specific MSRs.

 * vmx_get_vmx_msr() and vmx_set_vmx_msr() return 1 when we handled a

 * VMX-specific MSR, or 0 when we haven't (and the caller should handle it

 * like all other MSRs).

 */

/* Returns 0 on success, non-0 otherwise. */

static int vmx_get_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)

{

	if (!nested_vmx_allowed(vcpu) && msr_index >= MSR_IA32_VMX_BASIC &&

		     msr_index <= MSR_IA32_VMX_TRUE_ENTRY_CTLS) {

		/*

		 * According to the spec, processors which do not support VMX

		 * should throw a #GP(0) when VMX capability MSRs are read.

		 */

		kvm_queue_exception_e(vcpu, GP_VECTOR, 0);

		return 1;

	}



	switch (msr_index) {

	case MSR_IA32_FEATURE_CONTROL:

		if (nested_vmx_allowed(vcpu)) {

			*pdata = to_vmx(vcpu)->nested.msr_ia32_feature_control;

			break;

		}

		return 0;

	case MSR_IA32_VMX_BASIC:

		/*

		 * This MSR reports some information about VMX support. We
@@ -2453,38 +2431,9 @@ static int vmx_get_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata) 
		*pdata = nested_vmx_ept_caps;

		break;

	default:

		return 0;

	}



	return 1;

}



static void vmx_leave_nested(struct kvm_vcpu *vcpu);



static int vmx_set_vmx_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)

{

	u32 msr_index = msr_info->index;

	u64 data = msr_info->data;

	bool host_initialized = msr_info->host_initiated;



	if (!nested_vmx_allowed(vcpu))

		return 0;



	if (msr_index == MSR_IA32_FEATURE_CONTROL) {

		if (!host_initialized &&

				to_vmx(vcpu)->nested.msr_ia32_feature_control

				& FEATURE_CONTROL_LOCKED)

			return 0;

		to_vmx(vcpu)->nested.msr_ia32_feature_control = data;

		if (host_initialized && data == 0)

			vmx_leave_nested(vcpu);

		return 1;

	}



	/*

	 * No need to treat VMX capability MSRs specially: If we don't handle

	 * them, handle_wrmsr will #GP(0), which is correct (they are readonly)

	 */

	return 0;

}
@@ -2530,13 +2479,20 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata) 
	case MSR_IA32_SYSENTER_ESP:

		data = vmcs_readl(GUEST_SYSENTER_ESP);

		break;

	case MSR_IA32_FEATURE_CONTROL:

		if (!nested_vmx_allowed(vcpu))

			return 1;

		data = to_vmx(vcpu)->nested.msr_ia32_feature_control;

		break;

	case MSR_IA32_VMX_BASIC ... MSR_IA32_VMX_VMFUNC:

		if (!nested_vmx_allowed(vcpu))

			return 1;

		return vmx_get_vmx_msr(vcpu, msr_index, pdata);

	case MSR_TSC_AUX:

		if (!to_vmx(vcpu)->rdtscp_enabled)

			return 1;

		/* Otherwise falls through */

	default:

		if (vmx_get_vmx_msr(vcpu, msr_index, pdata))

			return 0;

		msr = find_msr_entry(to_vmx(vcpu), msr_index);

		if (msr) {

			data = msr->data;
@@ -2549,6 +2505,8 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata) 
	return 0;

}



static void vmx_leave_nested(struct kvm_vcpu *vcpu);



/*

 * Writes msr value into into the appropriate "register".

 * Returns 0 on success, non-0 otherwise.
@@ -2603,6 +2561,17 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 
	case MSR_IA32_TSC_ADJUST:

		ret = kvm_set_msr_common(vcpu, msr_info);

		break;

	case MSR_IA32_FEATURE_CONTROL:

		if (!nested_vmx_allowed(vcpu) ||

		    (to_vmx(vcpu)->nested.msr_ia32_feature_control &

		     FEATURE_CONTROL_LOCKED && !msr_info->host_initiated))

			return 1;

		vmx->nested.msr_ia32_feature_control = data;

		if (msr_info->host_initiated && data == 0)

			vmx_leave_nested(vcpu);

		break;

	case MSR_IA32_VMX_BASIC ... MSR_IA32_VMX_VMFUNC:

		return 1; /* they are read-only */

	case MSR_TSC_AUX:

		if (!vmx->rdtscp_enabled)

			return 1;
@@ -2611,8 +2580,6 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 
			return 1;

		/* Otherwise falls through */

	default:

		if (vmx_set_vmx_msr(vcpu, msr_info))

			break;

		msr = find_msr_entry(vmx, msr_index);

		if (msr) {

			msr->data = data;