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, 149 insertions, 0 deletions

diff --git a/include/trace/events/rpm.h b/include/trace/events/rpm.h
new file mode 100644
index 000000000..2b0b4b6ef
--- /dev/null
+++ b/include/trace/events/rpm.h
@@ -0,0 +1,149 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM rpm
+
+#if !defined(_TRACE_RUNTIME_POWER_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_RUNTIME_POWER_H
+
+#include <linux/ktime.h>
+#include <linux/tracepoint.h>
+
+struct device;
+
+/*
+ * The rpm_internal events are used for tracing some important
+ * runtime pm internal functions.
+ */
+DECLARE_EVENT_CLASS(rpm_internal,
+
+	TP_PROTO(struct device *dev, int flags),
+
+	TP_ARGS(dev, flags),
+
+	TP_STRUCT__entry(
+		__string(       name,		dev_name(dev)	)
+		__field(        int,            flags           )
+		__field(        int ,   	usage_count	)
+		__field(        int ,   	disable_depth   )
+		__field(        int ,   	runtime_auto	)
+		__field(        int ,   	request_pending	)
+		__field(        int ,   	irq_safe	)
+		__field(        int ,   	child_count 	)
+	),
+
+	TP_fast_assign(
+		__assign_str(name);
+		__entry->flags = flags;
+		__entry->usage_count = atomic_read(
+			&dev->power.usage_count);
+		__entry->disable_depth = dev->power.disable_depth;
+		__entry->runtime_auto = dev->power.runtime_auto;
+		__entry->request_pending = dev->power.request_pending;
+		__entry->irq_safe = dev->power.irq_safe;
+		__entry->child_count = atomic_read(
+			&dev->power.child_count);
+	),
+
+	TP_printk("%s flags-%x cnt-%-2d dep-%-2d auto-%-1d p-%-1d"
+			" irq-%-1d child-%d",
+			__get_str(name), __entry->flags,
+			__entry->usage_count,
+			__entry->disable_depth,
+			__entry->runtime_auto,
+			__entry->request_pending,
+			__entry->irq_safe,
+			__entry->child_count
+		 )
+);
+DEFINE_EVENT(rpm_internal, rpm_suspend,
+
+	TP_PROTO(struct device *dev, int flags),
+
+	TP_ARGS(dev, flags)
+);
+DEFINE_EVENT(rpm_internal, rpm_resume,
+
+	TP_PROTO(struct device *dev, int flags),
+
+	TP_ARGS(dev, flags)
+);
+DEFINE_EVENT(rpm_internal, rpm_idle,
+
+	TP_PROTO(struct device *dev, int flags),
+
+	TP_ARGS(dev, flags)
+);
+DEFINE_EVENT(rpm_internal, rpm_usage,
+
+	TP_PROTO(struct device *dev, int flags),
+
+	TP_ARGS(dev, flags)
+);
+
+TRACE_EVENT(rpm_return_int,
+	TP_PROTO(struct device *dev, unsigned long ip, int ret),
+	TP_ARGS(dev, ip, ret),
+
+	TP_STRUCT__entry(
+		__string(       name,		dev_name(dev))
+		__field(	unsigned long,		ip	)
+		__field(	int,			ret	)
+	),
+
+	TP_fast_assign(
+		__assign_str(name);
+		__entry->ip = ip;
+		__entry->ret = ret;
+	),
+
+	TP_printk("%pS:%s ret=%d", (void *)__entry->ip, __get_str(name),
+		__entry->ret)
+);
+
+#define RPM_STATUS_STRINGS \
+	EM(RPM_INVALID, "RPM_INVALID") \
+	EM(RPM_ACTIVE, "RPM_ACTIVE") \
+	EM(RPM_RESUMING, "RPM_RESUMING") \
+	EM(RPM_SUSPENDED, "RPM_SUSPENDED") \
+	EMe(RPM_SUSPENDING, "RPM_SUSPENDING")
+
+/* Enums require being exported to userspace, for user tool parsing. */
+#undef EM
+#undef EMe
+#define EM(a, b)	TRACE_DEFINE_ENUM(a);
+#define EMe(a, b)	TRACE_DEFINE_ENUM(a);
+
+RPM_STATUS_STRINGS
+
+/*
+ * Now redefine the EM() and EMe() macros to map the enums to the strings that
+ * will be printed in the output.
+ */
+#undef EM
+#undef EMe
+#define EM(a, b)	{ a, b },
+#define EMe(a, b)	{ a, b }
+
+TRACE_EVENT(rpm_status,
+	TP_PROTO(struct device *dev, enum rpm_status status),
+	TP_ARGS(dev, status),
+
+	TP_STRUCT__entry(
+		__string(name,	dev_name(dev))
+		__field(int,	status)
+	),
+
+	TP_fast_assign(
+		__assign_str(name);
+		__entry->status = status;
+	),
+
+	TP_printk("%s status=%s", __get_str(name),
+		__print_symbolic(__entry->status, RPM_STATUS_STRINGS))
+);
+
+#endif /* _TRACE_RUNTIME_POWER_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>