[Part2 PATCH v7 23/38] KVM: SVM: Reserve ASID range for SEV guest

[Brijesh Singh]

A SEV-enabled guest must use ASIDs from the defined subset, while non-SEV
guests can use the remaining ASID range. The range of allowed SEV guest
ASIDs is [1 - CPUID_8000_001F[ECX][31:0]].

Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: "Radim KrÄmÃÅ" <rkrcmar@xxxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: kvm@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Improvements-by: Borislav Petkov <bp@xxxxxxx>
Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
Reviewed-by: Borislav Petkov <bp@xxxxxxx>
---
 arch/x86/kvm/svm.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index be2e98c01b22..d4b62536e305 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -323,6 +323,8 @@ enum {
 
 #define VMCB_AVIC_APIC_BAR_MASK		0xFFFFFFFFFF000ULL
 
+static unsigned int max_sev_asid;
+
 static inline void mark_all_dirty(struct vmcb *vmcb)
 {
 	vmcb->control.clean = 0;
@@ -787,7 +789,7 @@ static int svm_hardware_enable(void)
 	sd->asid_generation = 1;
 	sd->max_asid = cpuid_ebx(SVM_CPUID_FUNC) - 1;
 	sd->next_asid = sd->max_asid + 1;
-	sd->min_asid = 1;
+	sd->min_asid = max_sev_asid + 1;
 
 	gdt = get_current_gdt_rw();
 	sd->tss_desc = (struct kvm_ldttss_desc *)(gdt + GDT_ENTRY_TSS);
@@ -1054,6 +1056,15 @@ static int avic_ga_log_notifier(u32 ga_tag)
 	return 0;
 }
 
+/*
+ * Get the maximum number of encrypted guests:
+ *  Fn8001_001F[ECX][31:0]: Number of supported guests.
+ */
+static __init void sev_hardware_setup(void)
+{
+	max_sev_asid = cpuid_ecx(0x8000001F);
+}
+
 static __init int svm_hardware_setup(void)
 {
 	int cpu;
@@ -1084,6 +1095,16 @@ static __init int svm_hardware_setup(void)
 		kvm_tsc_scaling_ratio_frac_bits = 32;
 	}
 
+	if (sev) {
+		if (boot_cpu_has(X86_FEATURE_SEV) &&
+		    IS_ENABLED(CONFIG_KVM_AMD_SEV)) {
+			sev_hardware_setup();
+			pr_info("SEV supported\n");
+		} else {
+			sev = false;
+		}
+	}
+
 	if (nested) {
 		printk(KERN_INFO "kvm: Nested Virtualization enabled\n");
 		kvm_enable_efer_bits(EFER_SVME | EFER_LMSLE);
-- 
2.9.5