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