linux-kernel - [Part2 PATCH v4 15/29] KVM: SVM: VMRUN should use assosiated ASID when SEV is enabled

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Message-Id: <20170919204627.3875-16-brijesh.singh@amd.com>
Date:   Tue, 19 Sep 2017 15:46:13 -0500
From:   Brijesh Singh <brijesh.singh@....com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Brijesh Singh <brijesh.singh@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Joerg Roedel <joro@...tes.org>, Borislav Petkov <bp@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>, x86@...nel.org
Subject: [Part2 PATCH v4 15/29] 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, SEV VM use SEV_CMD_ACTIVATE
command to bind a particular ASID to the guest. Lets make sure that the
VMCB is programmed with the bound ASID before a VMRUN.

Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: "Radim Krčmář" <rkrcmar@...hat.com>
Cc: Joerg Roedel <joro@...tes.org>
Cc: Borislav Petkov <bp@...e.de>
Cc: Tom Lendacky <thomas.lendacky@....com>
Cc: x86@...nel.org
Cc: kvm@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Brijesh Singh <brijesh.singh@....com>
---
 arch/x86/kvm/svm.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 56 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 229bb7d09c44..0149bfa75bb2 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_cpu;
 };
 
 /*
@@ -336,6 +339,13 @@ static inline bool sev_guest(struct kvm *kvm)
 	return sev->active;
 }
 
+static inline int sev_get_asid(struct kvm *kvm)
+{
+	struct kvm_sev_info *sev = &kvm->arch.sev_info;
+
+	return sev->asid;
+}
+
 static inline void mark_all_dirty(struct vmcb *vmcb)
 {
 	vmcb->control.clean = 0;
@@ -546,6 +556,9 @@ struct svm_cpu_data {
 	struct kvm_ldttss_desc *tss_desc;
 
 	struct page *save_area;
+
+	/* index = sev_asid, value = vmcb pointer */
+	struct vmcb **sev_vmcbs;
 };
 
 static DEFINE_PER_CPU(struct svm_cpu_data *, svm_data);
@@ -859,6 +872,7 @@ 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);
 }
@@ -872,11 +886,18 @@ static int svm_cpu_init(int cpu)
 	if (!sd)
 		return -ENOMEM;
 	sd->cpu = cpu;
-	sd->save_area = alloc_page(GFP_KERNEL);
 	r = -ENOMEM;
+	sd->save_area = alloc_page(GFP_KERNEL);
 	if (!sd->save_area)
 		goto err_1;
 
+	if (svm_sev_enabled()) {
+		r = -ENOMEM;
+		sd->sev_vmcbs = kmalloc((max_sev_asid + 1) * sizeof(void *), GFP_KERNEL);
+		if (!sd->sev_vmcbs)
+			goto err_1;
+	}
+
 	per_cpu(svm_data, cpu) = sd;
 
 	return 0;
@@ -1503,7 +1524,8 @@ static void sev_firmware_exit(void)
 static void sev_asid_free(struct kvm *kvm)
 {
 	struct kvm_sev_info *sev = &kvm->arch.sev_info;
-	int pos, asid;
+	struct svm_cpu_data *sd;
+	int pos, asid, cpu;
 
 	if (svm_sev_enabled())
 		return;
@@ -1511,6 +1533,11 @@ static void sev_asid_free(struct kvm *kvm)
 	asid = sev->asid;
 	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 void sev_vm_destroy(struct kvm *kvm)
@@ -4444,12 +4471,39 @@ static void reload_tss(struct kvm_vcpu *vcpu)
 	load_TR_desc();
 }
 
+static void pre_sev_run(struct vcpu_svm *svm, int cpu)
+{
+	struct svm_cpu_data *sd = per_cpu(svm_data, cpu);
+	int asid = sev_get_asid(svm->vcpu.kvm);
+
+	/* 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_cpu == cpu)
+		return;
+
+	svm->last_cpu = 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, cpu);
+
 	/* FIXME: handle wraparound of asid_generation */
 	if (svm->asid_generation != sd->asid_generation)
 		new_asid(svm, sd);
-- 
2.9.5