linux-kernel - [RFC Part2 PATCH v3 14/26] KVM: SVM: VMRUN should use assosiated ASID when SEV is enabled

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Message-Id: <20170724200303.12197-15-brijesh.singh@amd.com>
Date:   Mon, 24 Jul 2017 15:02:51 -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 14/26] KVM: SVM: VMRUN should use assosiated ASID when SEV is enabled

SEV hardware uses ASIDs to associate memory encryption key with the
guest VMs. During the guest creation time, we use SEV_CMD_ACTIVATE
command to bind a particular ASID to the guest. Lets make sure that
VMCB is programmed with the binded ASID before a VMRUN.

Signed-off-by: Brijesh Singh <brijesh.singh@....com>
---
 arch/x86/kvm/svm.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index e99a572..72f7c27 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -213,6 +213,9 @@ struct vcpu_svm {
 	 */
 	struct list_head ir_list;
 	spinlock_t ir_list_lock;
+
+	/* which host cpu was used for running this vcpu */
+	unsigned int last_cpuid;
 };
 
 /*
@@ -573,6 +576,8 @@ struct svm_cpu_data {
 	struct kvm_ldttss_desc *tss_desc;
 
 	struct page *save_area;
+
+	struct vmcb **sev_vmcbs;  /* index = sev_asid, value = vmcb pointer */
 };
 
 static DEFINE_PER_CPU(struct svm_cpu_data *, svm_data);
@@ -886,6 +891,7 @@ static void svm_cpu_uninit(int cpu)
 		return;
 
 	per_cpu(svm_data, raw_smp_processor_id()) = NULL;
+	kfree(sd->sev_vmcbs);
 	__free_page(sd->save_area);
 	kfree(sd);
 }
@@ -904,6 +910,14 @@ static int svm_cpu_init(int cpu)
 	if (!sd->save_area)
 		goto err_1;
 
+	if (svm_sev_enabled()) {
+		sd->sev_vmcbs = kmalloc((max_sev_asid + 1) * sizeof(void *),
+					GFP_KERNEL);
+		r = -ENOMEM;
+		if (!sd->sev_vmcbs)
+			goto err_1;
+	}
+
 	per_cpu(svm_data, cpu) = sd;
 
 	return 0;
@@ -4442,12 +4456,40 @@ static void reload_tss(struct kvm_vcpu *vcpu)
 	load_TR_desc();
 }
 
+static void pre_sev_run(struct vcpu_svm *svm)
+{
+	int cpu = raw_smp_processor_id();
+	int asid = sev_get_asid(svm->vcpu.kvm);
+	struct svm_cpu_data *sd = per_cpu(svm_data, cpu);
+
+	/* Assign the asid allocated with this SEV guest */
+	svm->vmcb->control.asid = asid;
+
+	/*
+	 * Flush guest TLB:
+	 *
+	 * 1) when different VMCB for the same ASID is to be run on the same host CPU.
+	 * 2) or this VMCB was executed on different host cpu in previous VMRUNs.
+	 */
+	if (sd->sev_vmcbs[asid] == svm->vmcb &&
+		svm->last_cpuid == cpu)
+		return;
+
+	svm->last_cpuid = cpu;
+	sd->sev_vmcbs[asid] = svm->vmcb;
+	svm->vmcb->control.tlb_ctl = TLB_CONTROL_FLUSH_ASID;
+	mark_dirty(svm->vmcb, VMCB_ASID);
+}
+
 static void pre_svm_run(struct vcpu_svm *svm)
 {
 	int cpu = raw_smp_processor_id();
 
 	struct svm_cpu_data *sd = per_cpu(svm_data, cpu);
 
+	if (sev_guest(svm->vcpu.kvm))
+		return pre_sev_run(svm);
+
 	/* FIXME: handle wraparound of asid_generation */
 	if (svm->asid_generation != sd->asid_generation)
 		new_asid(svm, sd);
@@ -5523,10 +5565,16 @@ static int sev_asid_new(void)
 
 static void sev_asid_free(int asid)
 {
-	int pos;
+	struct svm_cpu_data *sd;
+	int pos, cpu;
 
 	pos = asid - 1;
 	clear_bit(pos, sev_asid_bitmap);
+
+	for_each_possible_cpu(cpu) {
+		sd = per_cpu(svm_data, cpu);
+		sd->sev_vmcbs[pos] = NULL;
+	}
 }
 
 static int sev_firmware_init(int *error)
-- 
2.9.4