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, 72 insertions, 0 deletions

diff --git a/drivers/scsi/aacraid/nark.c b/drivers/scsi/aacraid/nark.c
new file mode 100644
index 000000000..4745a99fb
--- /dev/null
+++ b/drivers/scsi/aacraid/nark.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *	Adaptec AAC series RAID controller driver
+ *
+ * based on the old aacraid driver that is..
+ * Adaptec aacraid device driver for Linux.
+ *
+ * Copyright (c) 2000-2010 Adaptec, Inc.
+ *               2010-2015 PMC-Sierra, Inc. (aacraid@pmc-sierra.com)
+ *		 2016-2017 Microsemi Corp. (aacraid@microsemi.com)
+ *
+ * Module Name:
+ *  nark.c
+ *
+ * Abstract: Hardware Device Interface for NEMER/ARK
+ */
+
+#include <linux/pci.h>
+#include <linux/blkdev.h>
+
+#include <scsi/scsi_host.h>
+
+#include "aacraid.h"
+
+/**
+ *	aac_nark_ioremap
+ *	@dev: device to ioremap
+ *	@size: mapping resize request
+ *
+ */
+static int aac_nark_ioremap(struct aac_dev * dev, u32 size)
+{
+	if (!size) {
+		iounmap(dev->regs.rx);
+		dev->regs.rx = NULL;
+		iounmap(dev->base);
+		dev->base = NULL;
+		return 0;
+	}
+	dev->base_start = pci_resource_start(dev->pdev, 2);
+	dev->regs.rx = ioremap((u64)pci_resource_start(dev->pdev, 0) |
+	  ((u64)pci_resource_start(dev->pdev, 1) << 32),
+	  sizeof(struct rx_registers) - sizeof(struct rx_inbound));
+	dev->base = NULL;
+	if (dev->regs.rx == NULL)
+		return -1;
+	dev->base = ioremap(dev->base_start, size);
+	if (dev->base == NULL) {
+		iounmap(dev->regs.rx);
+		dev->regs.rx = NULL;
+		return -1;
+	}
+	dev->IndexRegs = &((struct rx_registers __iomem *)dev->base)->IndexRegs;
+	return 0;
+}
+
+/**
+ *	aac_nark_init	-	initialize an NEMER/ARK Split Bar card
+ *	@dev: device to configure
+ *
+ */
+
+int aac_nark_init(struct aac_dev * dev)
+{
+	/*
+	 *	Fill in the function dispatch table.
+	 */
+	dev->a_ops.adapter_ioremap = aac_nark_ioremap;
+	dev->a_ops.adapter_comm = aac_rx_select_comm;
+
+	return _aac_rx_init(dev);
+}