KVM: SEV: Do cache maintenance on the source VM during intra-host migrationgrafted

Manually perform cache maintenance on the source VM during intra-host
migration to ensure no stale data is left in CPU caches after the VM is
destroyed.  Because the source VM is "converted" to a non-SEV VM, KVM's
memory reclaim flows won't trigger cache maintenance, e.g. when all guest
memory is reclaimed in response to detaching from the mmu_notifier.

Note, relying on the destination VM to do cache maintenance isn't an option
as KVM doesn't require identical guest memory configurations, i.e. the
source VM may have access to memory that the destination VM does not.
Enforcing equivalent memory configurations is infeasible, as it would
require a *deep* comparison of memslots, e.g. to verify that not only are
the memslot identical, but what the memslots point at is also identical.

Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration")
Cc: stable@vger.kernel.org
Reported-by: Stefan Teodorescu <fane@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260923163721.1584779-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 205 insertions, 0 deletions

diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
new file mode 100644
index 000000000..6b4a118d1
--- /dev/null
+++ b/include/kvm/arm_pmu.h
@@ -0,0 +1,205 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2015 Linaro Ltd.
+ * Author: Shannon Zhao <shannon.zhao@linaro.org>
+ */
+
+#ifndef __ASM_ARM_KVM_PMU_H
+#define __ASM_ARM_KVM_PMU_H
+
+#include <linux/perf_event.h>
+#include <linux/perf/arm_pmuv3.h>
+
+#define KVM_ARMV8_PMU_MAX_COUNTERS	32
+
+/* PPI #23 - architecturally specified for GICv5 */
+#define KVM_ARMV8_PMU_GICV5_IRQ		0x20000017
+
+#if IS_ENABLED(CONFIG_HW_PERF_EVENTS) && IS_ENABLED(CONFIG_KVM)
+struct kvm_pmc {
+	u8 idx;	/* index into the pmu->pmc array */
+	struct perf_event *perf_event;
+};
+
+struct kvm_pmu_events {
+	u64 events_host;
+	u64 events_guest;
+};
+
+struct kvm_pmu {
+	struct irq_work overflow_work;
+	struct kvm_pmu_events events;
+	struct kvm_pmc pmc[KVM_ARMV8_PMU_MAX_COUNTERS];
+	int irq_num;
+	bool created;
+};
+
+struct arm_pmu_entry {
+	struct list_head entry;
+	struct arm_pmu *arm_pmu;
+};
+
+bool kvm_supports_guest_pmuv3(void);
+#define kvm_arm_pmu_irq_initialized(v)	((v)->arch.pmu.irq_num != 0)
+u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu, u64 select_idx);
+void kvm_pmu_set_counter_value(struct kvm_vcpu *vcpu, u64 select_idx, u64 val);
+void kvm_pmu_set_counter_value_user(struct kvm_vcpu *vcpu, u64 select_idx, u64 val);
+u64 kvm_pmu_implemented_counter_mask(struct kvm_vcpu *vcpu);
+u64 kvm_pmu_accessible_counter_mask(struct kvm_vcpu *vcpu);
+u64 kvm_pmu_get_pmceid(struct kvm_vcpu *vcpu, bool pmceid1);
+void kvm_pmu_vcpu_init(struct kvm_vcpu *vcpu);
+void kvm_pmu_vcpu_destroy(struct kvm_vcpu *vcpu);
+void kvm_pmu_reprogram_counter_mask(struct kvm_vcpu *vcpu, u64 val);
+void kvm_pmu_flush_hwstate(struct kvm_vcpu *vcpu);
+void kvm_pmu_sync_hwstate(struct kvm_vcpu *vcpu);
+bool kvm_pmu_should_notify_user(struct kvm_vcpu *vcpu);
+bool kvm_pmu_update_run(struct kvm_vcpu *vcpu);
+void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, u64 val);
+void kvm_pmu_handle_pmcr(struct kvm_vcpu *vcpu, u64 val);
+void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, u64 data,
+				    u64 select_idx);
+void kvm_vcpu_reload_pmu(struct kvm_vcpu *vcpu);
+int kvm_arm_pmu_v3_set_attr(struct kvm_vcpu *vcpu,
+			    struct kvm_device_attr *attr);
+int kvm_arm_pmu_v3_get_attr(struct kvm_vcpu *vcpu,
+			    struct kvm_device_attr *attr);
+int kvm_arm_pmu_v3_has_attr(struct kvm_vcpu *vcpu,
+			    struct kvm_device_attr *attr);
+int kvm_arm_pmu_v3_enable(struct kvm_vcpu *vcpu);
+
+struct kvm_pmu_events *kvm_get_pmu_events(void);
+void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu);
+void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu);
+void kvm_vcpu_pmu_resync_el0(void);
+
+#define kvm_vcpu_has_pmu(vcpu)					\
+	(vcpu_has_feature(vcpu, KVM_ARM_VCPU_PMU_V3))
+
+#define kvm_vcpu_has_pmuv3_strict(vcpu)				\
+	(vcpu_has_feature(vcpu, KVM_ARM_VCPU_PMU_V3_STRICT))
+
+/*
+ * Updates the vcpu's view of the pmu events for this cpu.
+ * Must be called before every vcpu run after disabling interrupts, to ensure
+ * that an interrupt cannot fire and update the structure.
+ */
+#define kvm_pmu_update_vcpu_events(vcpu)				\
+	do {								\
+		if (!has_vhe() && system_supports_pmuv3())		\
+			vcpu->arch.pmu.events = *kvm_get_pmu_events();	\
+	} while (0)
+
+u8 kvm_arm_pmu_get_pmuver_limit(void);
+u64 kvm_pmu_evtyper_mask(struct kvm *kvm);
+int kvm_arm_set_default_pmu(struct kvm *kvm);
+u8 kvm_arm_pmu_get_max_counters(struct kvm *kvm);
+
+u64 kvm_vcpu_read_pmcr(struct kvm_vcpu *vcpu);
+bool kvm_pmu_counter_is_hyp(struct kvm_vcpu *vcpu, unsigned int idx);
+void kvm_pmu_nested_transition(struct kvm_vcpu *vcpu);
+#else
+struct kvm_pmu {
+};
+
+static inline bool kvm_supports_guest_pmuv3(void)
+{
+	return false;
+}
+
+#define kvm_arm_pmu_irq_initialized(v)	(false)
+static inline u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu,
+					    u64 select_idx)
+{
+	return 0;
+}
+static inline void kvm_pmu_set_counter_value(struct kvm_vcpu *vcpu,
+					     u64 select_idx, u64 val) {}
+static inline void kvm_pmu_set_counter_value_user(struct kvm_vcpu *vcpu,
+						  u64 select_idx, u64 val) {}
+static inline u64 kvm_pmu_implemented_counter_mask(struct kvm_vcpu *vcpu)
+{
+	return 0;
+}
+static inline u64 kvm_pmu_accessible_counter_mask(struct kvm_vcpu *vcpu)
+{
+	return 0;
+}
+static inline void kvm_pmu_vcpu_init(struct kvm_vcpu *vcpu) {}
+static inline void kvm_pmu_vcpu_destroy(struct kvm_vcpu *vcpu) {}
+static inline void kvm_pmu_reprogram_counter_mask(struct kvm_vcpu *vcpu, u64 val) {}
+static inline void kvm_pmu_flush_hwstate(struct kvm_vcpu *vcpu) {}
+static inline void kvm_pmu_sync_hwstate(struct kvm_vcpu *vcpu) {}
+static inline bool kvm_pmu_should_notify_user(struct kvm_vcpu *vcpu)
+{
+	return false;
+}
+static inline bool kvm_pmu_update_run(struct kvm_vcpu *vcpu) { return false; }
+static inline void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, u64 val) {}
+static inline void kvm_pmu_handle_pmcr(struct kvm_vcpu *vcpu, u64 val) {}
+static inline void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu,
+						  u64 data, u64 select_idx) {}
+static inline int kvm_arm_pmu_v3_set_attr(struct kvm_vcpu *vcpu,
+					  struct kvm_device_attr *attr)
+{
+	return -ENXIO;
+}
+static inline int kvm_arm_pmu_v3_get_attr(struct kvm_vcpu *vcpu,
+					  struct kvm_device_attr *attr)
+{
+	return -ENXIO;
+}
+static inline int kvm_arm_pmu_v3_has_attr(struct kvm_vcpu *vcpu,
+					  struct kvm_device_attr *attr)
+{
+	return -ENXIO;
+}
+static inline int kvm_arm_pmu_v3_enable(struct kvm_vcpu *vcpu)
+{
+	return 0;
+}
+static inline u64 kvm_pmu_get_pmceid(struct kvm_vcpu *vcpu, bool pmceid1)
+{
+	return 0;
+}
+
+#define kvm_vcpu_has_pmu(vcpu)		({ false; })
+#define kvm_vcpu_has_pmuv3_strict(vcpu)	({ false; })
+static inline void kvm_pmu_update_vcpu_events(struct kvm_vcpu *vcpu) {}
+static inline void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu) {}
+static inline void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu) {}
+static inline void kvm_vcpu_reload_pmu(struct kvm_vcpu *vcpu) {}
+static inline u8 kvm_arm_pmu_get_pmuver_limit(void)
+{
+	return 0;
+}
+static inline u64 kvm_pmu_evtyper_mask(struct kvm *kvm)
+{
+	return 0;
+}
+static inline void kvm_vcpu_pmu_resync_el0(void) {}
+
+static inline int kvm_arm_set_default_pmu(struct kvm *kvm)
+{
+	return -ENODEV;
+}
+
+static inline u8 kvm_arm_pmu_get_max_counters(struct kvm *kvm)
+{
+	return 0;
+}
+
+static inline u64 kvm_vcpu_read_pmcr(struct kvm_vcpu *vcpu)
+{
+	return 0;
+}
+
+static inline bool kvm_pmu_counter_is_hyp(struct kvm_vcpu *vcpu, unsigned int idx)
+{
+	return false;
+}
+
+static inline void kvm_pmu_nested_transition(struct kvm_vcpu *vcpu) {}
+
+#endif
+
+#endif