Commit add5e2f0 authored by Tom Lendacky's avatar Tom Lendacky Committed by Paolo Bonzini
Browse files

KVM: SVM: Add support for the SEV-ES VMSA 



Allocate a page during vCPU creation to be used as the encrypted VM save
area (VMSA) for the SEV-ES guest. Provide a flag in the kvm_vcpu_arch
structure that indicates whether the guest state is protected.

When freeing a VMSA page that has been encrypted, the cache contents must
be flushed using the MSR_AMD64_VM_PAGE_FLUSH before freeing the page.

[ i386 build warnings ]
Reported-by: default avatarkernel test robot <lkp@intel.com>
Signed-off-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Message-Id: <fde272b17eec804f3b9db18c131262fe074015c5.1607620209.git.thomas.lendacky@amd.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 0f60bde1

arch/x86/include/asm/kvm_host.h

+3 −0
Original line number Diff line number Diff line
@@ -805,6 +805,9 @@ struct kvm_vcpu_arch { 
		 */

		bool enforce;

	} pv_cpuid;



	/* Protected Guests */

	bool guest_state_protected;

};



struct kvm_lpage_info {

arch/x86/kvm/svm/sev.c

+67 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/psp-sev.h>

#include <linux/pagemap.h>

#include <linux/swap.h>

#include <linux/processor.h>



#include "x86.h"

#include "svm.h"
@@ -1190,6 +1191,72 @@ void sev_hardware_teardown(void) 
	sev_flush_asids();

}



/*

 * Pages used by hardware to hold guest encrypted state must be flushed before

 * returning them to the system.

 */

static void sev_flush_guest_memory(struct vcpu_svm *svm, void *va,

				   unsigned long len)

{

	/*

	 * If hardware enforced cache coherency for encrypted mappings of the

	 * same physical page is supported, nothing to do.

	 */

	if (boot_cpu_has(X86_FEATURE_SME_COHERENT))

		return;



	/*

	 * If the VM Page Flush MSR is supported, use it to flush the page

	 * (using the page virtual address and the guest ASID).

	 */

	if (boot_cpu_has(X86_FEATURE_VM_PAGE_FLUSH)) {

		struct kvm_sev_info *sev;

		unsigned long va_start;

		u64 start, stop;



		/* Align start and stop to page boundaries. */

		va_start = (unsigned long)va;

		start = (u64)va_start & PAGE_MASK;

		stop = PAGE_ALIGN((u64)va_start + len);



		if (start < stop) {

			sev = &to_kvm_svm(svm->vcpu.kvm)->sev_info;



			while (start < stop) {

				wrmsrl(MSR_AMD64_VM_PAGE_FLUSH,

				       start | sev->asid);



				start += PAGE_SIZE;

			}



			return;

		}



		WARN(1, "Address overflow, using WBINVD\n");

	}



	/*

	 * Hardware should always have one of the above features,

	 * but if not, use WBINVD and issue a warning.

	 */

	WARN_ONCE(1, "Using WBINVD to flush guest memory\n");

	wbinvd_on_all_cpus();

}



void sev_free_vcpu(struct kvm_vcpu *vcpu)

{

	struct vcpu_svm *svm;



	if (!sev_es_guest(vcpu->kvm))

		return;



	svm = to_svm(vcpu);



	if (vcpu->arch.guest_state_protected)

		sev_flush_guest_memory(svm, svm->vmsa, PAGE_SIZE);

	__free_page(virt_to_page(svm->vmsa));

}



void pre_sev_run(struct vcpu_svm *svm, int cpu)

{

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

arch/x86/kvm/svm/svm.c

+22 −2
Original line number Diff line number Diff line
@@ -1288,6 +1288,7 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu) 
{

	struct vcpu_svm *svm;

	struct page *vmcb_page;

	struct page *vmsa_page = NULL;

	int err;



	BUILD_BUG_ON(offsetof(struct vcpu_svm, vcpu) != 0);
@@ -1298,9 +1299,19 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu) 
	if (!vmcb_page)

		goto out;



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

		/*

		 * SEV-ES guests require a separate VMSA page used to contain

		 * the encrypted register state of the guest.

		 */

		vmsa_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);

		if (!vmsa_page)

			goto error_free_vmcb_page;

	}



	err = avic_init_vcpu(svm);

	if (err)

		goto error_free_vmcb_page;

		goto error_free_vmsa_page;



	/* We initialize this flag to true to make sure that the is_running

	 * bit would be set the first time the vcpu is loaded.
@@ -1310,12 +1321,16 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu) 


	svm->msrpm = svm_vcpu_alloc_msrpm();

	if (!svm->msrpm)

		goto error_free_vmcb_page;

		goto error_free_vmsa_page;



	svm_vcpu_init_msrpm(vcpu, svm->msrpm);



	svm->vmcb = page_address(vmcb_page);

	svm->vmcb_pa = __sme_set(page_to_pfn(vmcb_page) << PAGE_SHIFT);



	if (vmsa_page)

		svm->vmsa = page_address(vmsa_page);



	svm->asid_generation = 0;

	init_vmcb(svm);
@@ -1324,6 +1339,9 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu) 


	return 0;



error_free_vmsa_page:

	if (vmsa_page)

		__free_page(vmsa_page);

error_free_vmcb_page:

	__free_page(vmcb_page);

out:
@@ -1351,6 +1369,8 @@ static void svm_free_vcpu(struct kvm_vcpu *vcpu) 


	svm_free_nested(svm);



	sev_free_vcpu(vcpu);



	__free_page(pfn_to_page(__sme_clr(svm->vmcb_pa) >> PAGE_SHIFT));

	__free_pages(virt_to_page(svm->msrpm), MSRPM_ALLOC_ORDER);

}

arch/x86/kvm/svm/svm.h

+5 −0
Original line number Diff line number Diff line
@@ -168,6 +168,10 @@ struct vcpu_svm { 
		DECLARE_BITMAP(read, MAX_DIRECT_ACCESS_MSRS);

		DECLARE_BITMAP(write, MAX_DIRECT_ACCESS_MSRS);

	} shadow_msr_intercept;



	/* SEV-ES support */

	struct vmcb_save_area *vmsa;

	struct ghcb *ghcb;

};



struct svm_cpu_data {
@@ -513,5 +517,6 @@ int svm_unregister_enc_region(struct kvm *kvm, 
void pre_sev_run(struct vcpu_svm *svm, int cpu);

void __init sev_hardware_setup(void);

void sev_hardware_teardown(void);

void sev_free_vcpu(struct kvm_vcpu *vcpu);



#endif

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