linux-kernel - [RFC Part2 PATCH v3 05/26] KVM: SVM: Reserve ASID range for SEV guest

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Message-Id: <20170724200303.12197-6-brijesh.singh@amd.com>
Date:   Mon, 24 Jul 2017 15:02:42 -0500
From:   Brijesh Singh <brijesh.singh@....com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org, kvm@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...e.de>,
        Joerg Roedel <joro@...tes.org>,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        \"Radim Krčmář\" 
        <rkrcmar@...hat.com>, Tom Lendacky <thomas.lendacky@....com>,
        Brijesh Singh <brijesh.singh@....com>
Subject: [RFC Part2 PATCH v3 05/26] KVM: SVM: Reserve ASID range for SEV guest

SEV-enabled guest must use ASIDs from the defined subset, while non-SEV
guests can use the remaining ASID range. The range of ASID allowed for
SEV-enabled guest is from 1 to a maximum value defined via CPUID
Fn8000_001f[ECX].

Signed-off-by: Brijesh Singh <brijesh.singh@....com>
---
 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 46f41bb..06bd902 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -319,6 +319,9 @@ enum {
 
 #define VMCB_AVIC_APIC_BAR_MASK		0xFFFFFFFFFF000ULL
 
+/* Secure Encrypted Virtualization */
+static unsigned int max_sev_asid;
+
 static inline void mark_all_dirty(struct vmcb *vmcb)
 {
 	vmcb->control.clean = 0;
@@ -769,7 +772,7 @@ 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);
@@ -1033,6 +1036,21 @@ static int avic_ga_log_notifier(u32 ga_tag)
 	return 0;
 }
 
+static __init void sev_hardware_setup(void)
+{
+	int nguests;
+
+	/*
+	 * Get maximum number of encrypted guest supported: Fn8001_001F[ECX]
+	 *     Bit 31:0: Number of supported guest
+	 */
+	nguests = cpuid_ecx(0x8000001F);
+	if (!nguests)
+		return;
+
+	max_sev_asid = nguests;
+}
+
 static __init int svm_hardware_setup(void)
 {
 	int cpu;
@@ -1063,6 +1081,9 @@ static __init int svm_hardware_setup(void)
 		kvm_tsc_scaling_ratio_frac_bits = 32;
 	}
 
+	if (boot_cpu_has(X86_FEATURE_SEV))
+		sev_hardware_setup();
+
 	if (nested) {
 		printk(KERN_INFO "kvm: Nested Virtualization enabled\n");
 		kvm_enable_efer_bits(EFER_SVME | EFER_LMSLE);
-- 
2.9.4