Commit a7fc06dd authored by Michael Roth's avatar Michael Roth Committed by Paolo Bonzini
Browse files

KVM: SVM: use .prepare_guest_switch() to handle CPU register save/setup 



Currently we save host state like user-visible host MSRs, and do some
initial guest register setup for MSR_TSC_AUX and MSR_AMD64_TSC_RATIO
in svm_vcpu_load(). Defer this until just before we enter the guest by
moving the handling to kvm_x86_ops.prepare_guest_switch() similarly to
how it is done for the VMX implementation.

Additionally, since handling of saving/restoring host user MSRs is the
same both with/without SEV-ES enabled, move that handling to common
code.

Suggested-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarMichael Roth <michael.roth@amd.com>
Message-Id: <20210202190126.2185715-4-michael.roth@amd.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 553cc15f

arch/x86/kvm/svm/sev.c

+1 −21
Original line number Diff line number Diff line
@@ -2066,11 +2066,10 @@ void sev_es_create_vcpu(struct vcpu_svm *svm) 
					    sev_enc_bit));

}



void sev_es_vcpu_load(struct vcpu_svm *svm, int cpu)

void sev_es_prepare_guest_switch(struct vcpu_svm *svm, unsigned int cpu)

{

	struct svm_cpu_data *sd = per_cpu(svm_data, cpu);

	struct vmcb_save_area *hostsa;

	unsigned int i;



	/*

	 * As an SEV-ES guest, hardware will restore the host state on VMEXIT,
@@ -2079,13 +2078,6 @@ void sev_es_vcpu_load(struct vcpu_svm *svm, int cpu) 
	 */

	vmsave(__sme_page_pa(sd->save_area));



	/*

	 * Certain MSRs are restored on VMEXIT, only save ones that aren't

	 * restored.

	 */

	for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++)

		rdmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);



	/* XCR0 is restored on VMEXIT, save the current host value */

	hostsa = (struct vmcb_save_area *)(page_address(sd->save_area) + 0x400);

	hostsa->xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);
@@ -2097,18 +2089,6 @@ void sev_es_vcpu_load(struct vcpu_svm *svm, int cpu) 
	hostsa->xss = host_xss;

}



void sev_es_vcpu_put(struct vcpu_svm *svm)

{

	unsigned int i;



	/*

	 * Certain MSRs are restored on VMEXIT and were saved with vmsave in

	 * sev_es_vcpu_load() above. Only restore ones that weren't.

	 */

	for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++)

		wrmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);

}



void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector)

{

	struct vcpu_svm *svm = to_svm(vcpu);

arch/x86/kvm/svm/svm.c

+52 −24
Original line number Diff line number Diff line
@@ -1366,6 +1366,7 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu) 
		svm->vmsa = page_address(vmsa_page);



	svm->asid_generation = 0;

	svm->guest_state_loaded = false;

	init_vmcb(svm);



	svm_init_osvw(vcpu);
@@ -1413,23 +1414,30 @@ static void svm_free_vcpu(struct kvm_vcpu *vcpu) 
	__free_pages(virt_to_page(svm->msrpm), MSRPM_ALLOC_ORDER);

}



static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)

static void svm_prepare_guest_switch(struct kvm_vcpu *vcpu)

{

	struct vcpu_svm *svm = to_svm(vcpu);

	struct svm_cpu_data *sd = per_cpu(svm_data, cpu);

	int i;

	struct svm_cpu_data *sd = per_cpu(svm_data, vcpu->cpu);

	unsigned int i;



	if (unlikely(cpu != vcpu->cpu)) {

		svm->asid_generation = 0;

		vmcb_mark_all_dirty(svm->vmcb);

	}

	if (svm->guest_state_loaded)

		return;



	if (sev_es_guest(svm->vcpu.kvm)) {

		sev_es_vcpu_load(svm, cpu);

	} else {

	/*

	 * Certain MSRs are restored on VMEXIT (sev-es), or vmload of host save

	 * area (non-sev-es). Save ones that aren't so we can restore them

	 * individually later.

	 */

	for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++)

		rdmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);



	/*

	 * Save additional host state that will be restored on VMEXIT (sev-es)

	 * or subsequent vmload of host save area.

	 */

	if (sev_es_guest(svm->vcpu.kvm)) {

		sev_es_prepare_guest_switch(svm, vcpu->cpu);

	} else {

		vmsave(__sme_page_pa(sd->save_area));

	}
@@ -1440,10 +1448,42 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu) 
			wrmsrl(MSR_AMD64_TSC_RATIO, tsc_ratio);

		}

	}



	/* This assumes that the kernel never uses MSR_TSC_AUX */

	if (static_cpu_has(X86_FEATURE_RDTSCP))

		wrmsrl(MSR_TSC_AUX, svm->tsc_aux);



	svm->guest_state_loaded = true;

}



static void svm_prepare_host_switch(struct kvm_vcpu *vcpu)

{

	struct vcpu_svm *svm = to_svm(vcpu);

	unsigned int i;



	if (!svm->guest_state_loaded)

		return;



	/*

	 * Certain MSRs are restored on VMEXIT (sev-es), or vmload of host save

	 * area (non-sev-es). Restore the ones that weren't.

	 */

	for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++)

		wrmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);



	svm->guest_state_loaded = false;

}



static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)

{

	struct vcpu_svm *svm = to_svm(vcpu);

	struct svm_cpu_data *sd = per_cpu(svm_data, cpu);



	if (unlikely(cpu != vcpu->cpu)) {

		svm->asid_generation = 0;

		vmcb_mark_all_dirty(svm->vmcb);

	}



	if (sd->current_vmcb != svm->vmcb) {

		sd->current_vmcb = svm->vmcb;

		indirect_branch_prediction_barrier();
@@ -1453,18 +1493,10 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu) 


static void svm_vcpu_put(struct kvm_vcpu *vcpu)

{

	struct vcpu_svm *svm = to_svm(vcpu);

	int i;



	avic_vcpu_put(vcpu);

	svm_prepare_host_switch(vcpu);



	++vcpu->stat.host_state_reload;

	if (sev_es_guest(svm->vcpu.kvm)) {

		sev_es_vcpu_put(svm);

	} else {

		for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++)

			wrmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);

	}

}



static unsigned long svm_get_rflags(struct kvm_vcpu *vcpu)
@@ -3620,10 +3652,6 @@ static void svm_flush_tlb_gva(struct kvm_vcpu *vcpu, gva_t gva) 
	invlpga(gva, svm->vmcb->control.asid);

}



static void svm_prepare_guest_switch(struct kvm_vcpu *vcpu)

{

}



static inline void sync_cr8_to_lapic(struct kvm_vcpu *vcpu)

{

	struct vcpu_svm *svm = to_svm(vcpu);

arch/x86/kvm/svm/svm.h

+3 −2
Original line number Diff line number Diff line
@@ -172,6 +172,8 @@ struct vcpu_svm { 
	u64 ghcb_sa_len;

	bool ghcb_sa_sync;

	bool ghcb_sa_free;



	bool guest_state_loaded;

};



struct svm_cpu_data {
@@ -567,9 +569,8 @@ int sev_handle_vmgexit(struct vcpu_svm *svm); 
int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in);

void sev_es_init_vmcb(struct vcpu_svm *svm);

void sev_es_create_vcpu(struct vcpu_svm *svm);

void sev_es_vcpu_load(struct vcpu_svm *svm, int cpu);

void sev_es_vcpu_put(struct vcpu_svm *svm);

void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector);

void sev_es_prepare_guest_switch(struct vcpu_svm *svm, unsigned int cpu);



/* vmenter.S */