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Subject[PATCH v10 12/16] KVM: x86: Introduce new KVM_FEATURE_SEV_LIVE_MIGRATION feature & Custom MSR.
Date
From: Ashish Kalra <ashish.kalra@amd.com>

Add new KVM_FEATURE_SEV_LIVE_MIGRATION feature for guest to check
for host-side support for SEV live migration. Also add a new custom
MSR_KVM_SEV_LIVE_MIGRATION for guest to enable the SEV live migration
feature.

Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
Documentation/virt/kvm/cpuid.rst | 5 +++++
Documentation/virt/kvm/msr.rst | 12 ++++++++++++
arch/x86/include/uapi/asm/kvm_para.h | 4 ++++
arch/x86/kvm/svm/sev.c | 13 +++++++++++++
arch/x86/kvm/svm/svm.c | 16 ++++++++++++++++
arch/x86/kvm/svm/svm.h | 2 ++
6 files changed, 52 insertions(+)

diff --git a/Documentation/virt/kvm/cpuid.rst b/Documentation/virt/kvm/cpuid.rst
index cf62162d4be2..0bdb6cdb12d3 100644
--- a/Documentation/virt/kvm/cpuid.rst
+++ b/Documentation/virt/kvm/cpuid.rst
@@ -96,6 +96,11 @@ KVM_FEATURE_MSI_EXT_DEST_ID 15 guest checks this feature bit
before using extended destination
ID bits in MSI address bits 11-5.

+KVM_FEATURE_SEV_LIVE_MIGRATION 16 guest checks this feature bit before
+ using the page encryption state
+ hypercall to notify the page state
+ change
+
KVM_FEATURE_CLOCKSOURCE_STABLE_BIT 24 host will warn if no guest-side
per-cpu warps are expected in
kvmclock
diff --git a/Documentation/virt/kvm/msr.rst b/Documentation/virt/kvm/msr.rst
index e37a14c323d2..020245d16087 100644
--- a/Documentation/virt/kvm/msr.rst
+++ b/Documentation/virt/kvm/msr.rst
@@ -376,3 +376,15 @@ data:
write '1' to bit 0 of the MSR, this causes the host to re-scan its queue
and check if there are more notifications pending. The MSR is available
if KVM_FEATURE_ASYNC_PF_INT is present in CPUID.
+
+MSR_KVM_SEV_LIVE_MIGRATION:
+ 0x4b564d08
+
+ Control SEV Live Migration features.
+
+data:
+ Bit 0 enables (1) or disables (0) host-side SEV Live Migration feature,
+ in other words, this is guest->host communication that it's properly
+ handling the shared pages list.
+
+ All other bits are reserved.
diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h
index 950afebfba88..f6bfa138874f 100644
--- a/arch/x86/include/uapi/asm/kvm_para.h
+++ b/arch/x86/include/uapi/asm/kvm_para.h
@@ -33,6 +33,7 @@
#define KVM_FEATURE_PV_SCHED_YIELD 13
#define KVM_FEATURE_ASYNC_PF_INT 14
#define KVM_FEATURE_MSI_EXT_DEST_ID 15
+#define KVM_FEATURE_SEV_LIVE_MIGRATION 16

#define KVM_HINTS_REALTIME 0

@@ -54,6 +55,7 @@
#define MSR_KVM_POLL_CONTROL 0x4b564d05
#define MSR_KVM_ASYNC_PF_INT 0x4b564d06
#define MSR_KVM_ASYNC_PF_ACK 0x4b564d07
+#define MSR_KVM_SEV_LIVE_MIGRATION 0x4b564d08

struct kvm_steal_time {
__u64 steal;
@@ -136,4 +138,6 @@ struct kvm_vcpu_pv_apf_data {
#define KVM_PV_EOI_ENABLED KVM_PV_EOI_MASK
#define KVM_PV_EOI_DISABLED 0x0

+#define KVM_SEV_LIVE_MIGRATION_ENABLED BIT_ULL(0)
+
#endif /* _UAPI_ASM_X86_KVM_PARA_H */
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index b0d324aed515..93f42b3d3e33 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1627,6 +1627,16 @@ int svm_page_enc_status_hc(struct kvm *kvm, unsigned long gpa,
return ret;
}

+void sev_update_migration_flags(struct kvm *kvm, u64 data)
+{
+ struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+
+ if (!sev_guest(kvm))
+ return;
+
+ sev->live_migration_enabled = !!(data & KVM_SEV_LIVE_MIGRATION_ENABLED);
+}
+
int svm_get_shared_pages_list(struct kvm *kvm,
struct kvm_shared_pages_list *list)
{
@@ -1639,6 +1649,9 @@ int svm_get_shared_pages_list(struct kvm *kvm,
if (!sev_guest(kvm))
return -ENOTTY;

+ if (!sev->live_migration_enabled)
+ return -EINVAL;
+
if (!list->size)
return -EINVAL;

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 58f89f83caab..43ea5061926f 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2903,6 +2903,9 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
svm->msr_decfg = data;
break;
}
+ case MSR_KVM_SEV_LIVE_MIGRATION:
+ sev_update_migration_flags(vcpu->kvm, data);
+ break;
case MSR_IA32_APICBASE:
if (kvm_vcpu_apicv_active(vcpu))
avic_update_vapic_bar(to_svm(vcpu), data);
@@ -3976,6 +3979,19 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
vcpu->arch.cr3_lm_rsvd_bits &= ~(1UL << (best->ebx & 0x3f));
}

+ /*
+ * If SEV guest then enable the Live migration feature.
+ */
+ if (sev_guest(vcpu->kvm)) {
+ struct kvm_cpuid_entry2 *best;
+
+ best = kvm_find_cpuid_entry(vcpu, KVM_CPUID_FEATURES, 0);
+ if (!best)
+ return;
+
+ best->eax |= (1 << KVM_FEATURE_SEV_LIVE_MIGRATION);
+ }
+
if (!kvm_vcpu_apicv_active(vcpu))
return;

diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 066ca2a9f1e6..e1bffc11e425 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -79,6 +79,7 @@ struct kvm_sev_info {
unsigned long pages_locked; /* Number of pages locked */
struct list_head regions_list; /* List of registered regions */
u64 ap_jump_table; /* SEV-ES AP Jump Table address */
+ bool live_migration_enabled;
/* List and count of shared pages */
int shared_pages_list_count;
struct list_head shared_pages_list;
@@ -592,6 +593,7 @@ int svm_unregister_enc_region(struct kvm *kvm,
void pre_sev_run(struct vcpu_svm *svm, int cpu);
void __init sev_hardware_setup(void);
void sev_hardware_teardown(void);
+void sev_update_migration_flags(struct kvm *kvm, u64 data);
void sev_free_vcpu(struct kvm_vcpu *vcpu);
int sev_handle_vmgexit(struct vcpu_svm *svm);
int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in);
--
2.17.1
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