KVM: SVM: Set the encryption mask for the SVM host save area

The SVM host save area is used to restore some host state on VMEXIT of an
SEV-ES guest. After allocating the save area, clear it and add the
encryption mask to the SVM host save area physical address that is
programmed into the VM_HSAVE_PA MSR.
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <b77aa28af6d7f1a0cb545959e08d6dc75e0c3cba.1607620209.git.thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/sev.c

@@ -30,7 +30,6 @@ unsigned int max_sev_asid;
 static unsigned int min_sev_asid;
 static unsigned long *sev_asid_bitmap;
 static unsigned long *sev_reclaim_asid_bitmap;
-#define __sme_page_pa(x) __sme_set(page_to_pfn(x) << PAGE_SHIFT)
 
 struct enc_region {
 	struct list_head list;

arch/x86/kvm/svm/svm.c

@@ -497,7 +497,7 @@ static int svm_hardware_enable(void)
 
 	wrmsrl(MSR_EFER, efer | EFER_SVME);
 
-	wrmsrl(MSR_VM_HSAVE_PA, page_to_pfn(sd->save_area) << PAGE_SHIFT);
+	wrmsrl(MSR_VM_HSAVE_PA, __sme_page_pa(sd->save_area));
 
 	if (static_cpu_has(X86_FEATURE_TSCRATEMSR)) {
 		wrmsrl(MSR_AMD64_TSC_RATIO, TSC_RATIO_DEFAULT);
@@ -565,6 +565,7 @@ static int svm_cpu_init(int cpu)
 	sd->save_area = alloc_page(GFP_KERNEL);
 	if (!sd->save_area)
 		goto free_cpu_data;
+	clear_page(page_address(sd->save_area));
 
 	if (svm_sev_enabled()) {
 		sd->sev_vmcbs = kmalloc_array(max_sev_asid + 1,

arch/x86/kvm/svm/svm.h

@@ -21,6 +21,8 @@
 
 #include <asm/svm.h>
 
+#define __sme_page_pa(x) __sme_set(page_to_pfn(x) << PAGE_SHIFT)
+
 static const u32 host_save_user_msrs[] = {
 #ifdef CONFIG_X86_64
 	MSR_STAR, MSR_LSTAR, MSR_CSTAR, MSR_SYSCALL_MASK, MSR_KERNEL_GS_BASE,