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Subject[Part2 PATCH v9 26/38] KVM: SVM: VMRUN should use associated ASID when SEV is enabled
Date
SEV hardware uses ASIDs to associate a memory encryption key with a
guest VM. During guest creation, a SEV VM uses the 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@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: x86@kernel.org
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
---
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 51186107eb22..cdbdc86d7aee 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;
};

/*
@@ -341,6 +344,13 @@ 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;
@@ -551,6 +561,9 @@ 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);
@@ -864,6 +877,7 @@ 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);
}
@@ -877,11 +891,18 @@ 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;
@@ -1498,10 +1519,16 @@ static int avic_init_backing_page(struct kvm_vcpu *vcpu)

static void __sev_asid_free(int asid)
{
- int pos;
+ struct svm_cpu_data *sd;
+ int cpu, pos;

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_asid_free(struct kvm *kvm)
@@ -4466,12 +4493,39 @@ 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
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