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, 98 insertions, 0 deletions

diff --git a/drivers/crypto/caam/debugfs.c b/drivers/crypto/caam/debugfs.c
new file mode 100644
index 000000000..718352b7a
--- /dev/null
+++ b/drivers/crypto/caam/debugfs.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
+/* Copyright 2019, 2023 NXP */
+
+#include <linux/debugfs.h>
+#include "compat.h"
+#include "debugfs.h"
+#include "regs.h"
+#include "intern.h"
+
+static int caam_debugfs_u64_get(void *data, u64 *val)
+{
+	*val = caam64_to_cpu(*(u64 *)data);
+	return 0;
+}
+
+static int caam_debugfs_u32_get(void *data, u64 *val)
+{
+	*val = caam32_to_cpu(*(u32 *)data);
+	return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(caam_fops_u32_ro, caam_debugfs_u32_get, NULL, "%llu\n");
+DEFINE_DEBUGFS_ATTRIBUTE(caam_fops_u64_ro, caam_debugfs_u64_get, NULL, "%llu\n");
+
+#ifdef CONFIG_CRYPTO_DEV_FSL_CAAM_CRYPTO_API_QI
+/*
+ * This is a counter for the number of times the congestion group (where all
+ * the request and response queueus are) reached congestion. Incremented
+ * each time the congestion callback is called with congested == true.
+ */
+static u64 times_congested;
+
+void caam_debugfs_qi_congested(void)
+{
+	times_congested++;
+}
+
+void caam_debugfs_qi_init(struct caam_drv_private *ctrlpriv)
+{
+	debugfs_create_file("qi_congested", 0444, ctrlpriv->ctl,
+			    &times_congested, &caam_fops_u64_ro);
+}
+#endif
+
+void caam_debugfs_init(struct caam_drv_private *ctrlpriv,
+		       struct caam_perfmon __force *perfmon,
+		       struct dentry *root)
+{
+	/*
+	 * FIXME: needs better naming distinction, as some amalgamation of
+	 * "caam" and nprop->full_name. The OF name isn't distinctive,
+	 * but does separate instances
+	 */
+
+	ctrlpriv->ctl = debugfs_create_dir("ctl", root);
+
+	debugfs_create_file("rq_dequeued", 0444, ctrlpriv->ctl,
+			    &perfmon->req_dequeued, &caam_fops_u64_ro);
+	debugfs_create_file("ob_rq_encrypted", 0444, ctrlpriv->ctl,
+			    &perfmon->ob_enc_req, &caam_fops_u64_ro);
+	debugfs_create_file("ib_rq_decrypted", 0444, ctrlpriv->ctl,
+			    &perfmon->ib_dec_req, &caam_fops_u64_ro);
+	debugfs_create_file("ob_bytes_encrypted", 0444, ctrlpriv->ctl,
+			    &perfmon->ob_enc_bytes, &caam_fops_u64_ro);
+	debugfs_create_file("ob_bytes_protected", 0444, ctrlpriv->ctl,
+			    &perfmon->ob_prot_bytes, &caam_fops_u64_ro);
+	debugfs_create_file("ib_bytes_decrypted", 0444, ctrlpriv->ctl,
+			    &perfmon->ib_dec_bytes, &caam_fops_u64_ro);
+	debugfs_create_file("ib_bytes_validated", 0444, ctrlpriv->ctl,
+			    &perfmon->ib_valid_bytes, &caam_fops_u64_ro);
+
+	/* Controller level - global status values */
+	debugfs_create_file("fault_addr", 0444, ctrlpriv->ctl,
+			    &perfmon->faultaddr, &caam_fops_u32_ro);
+	debugfs_create_file("fault_detail", 0444, ctrlpriv->ctl,
+			    &perfmon->faultdetail, &caam_fops_u32_ro);
+	debugfs_create_file("fault_status", 0444, ctrlpriv->ctl,
+			    &perfmon->status, &caam_fops_u32_ro);
+
+	if (ctrlpriv->optee_en)
+		return;
+
+	/* Internal covering keys (useful in non-secure mode only) */
+	ctrlpriv->ctl_kek_wrap.data = (__force void *)&ctrlpriv->ctrl->kek[0];
+	ctrlpriv->ctl_kek_wrap.size = KEK_KEY_SIZE * sizeof(u32);
+	debugfs_create_blob("kek", 0444, ctrlpriv->ctl,
+			    &ctrlpriv->ctl_kek_wrap);
+
+	ctrlpriv->ctl_tkek_wrap.data = (__force void *)&ctrlpriv->ctrl->tkek[0];
+	ctrlpriv->ctl_tkek_wrap.size = KEK_KEY_SIZE * sizeof(u32);
+	debugfs_create_blob("tkek", 0444, ctrlpriv->ctl,
+			    &ctrlpriv->ctl_tkek_wrap);
+
+	ctrlpriv->ctl_tdsk_wrap.data = (__force void *)&ctrlpriv->ctrl->tdsk[0];
+	ctrlpriv->ctl_tdsk_wrap.size = KEK_KEY_SIZE * sizeof(u32);
+	debugfs_create_blob("tdsk", 0444, ctrlpriv->ctl,
+			    &ctrlpriv->ctl_tdsk_wrap);
+}