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, 65 insertions, 0 deletions

diff --git a/arch/mips/boot/ecoff.h b/arch/mips/boot/ecoff.h
new file mode 100644
index 000000000..5be79ebfc
--- /dev/null
+++ b/arch/mips/boot/ecoff.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Some ECOFF definitions.
+ */
+
+#include <stdint.h>
+
+typedef struct filehdr {
+	uint16_t	f_magic;	/* magic number */
+	uint16_t	f_nscns;	/* number of sections */
+	int32_t		f_timdat;	/* time & date stamp */
+	int32_t		f_symptr;	/* file pointer to symbolic header */
+	int32_t		f_nsyms;	/* sizeof(symbolic hdr) */
+	uint16_t	f_opthdr;	/* sizeof(optional hdr) */
+	uint16_t	f_flags;	/* flags */
+} FILHDR;
+#define FILHSZ	sizeof(FILHDR)
+
+#define MIPSEBMAGIC	0x160
+#define MIPSELMAGIC	0x162
+
+typedef struct scnhdr {
+	char		s_name[8];	/* section name */
+	int32_t		s_paddr;	/* physical address, aliased s_nlib */
+	int32_t		s_vaddr;	/* virtual address */
+	int32_t		s_size;		/* section size */
+	int32_t		s_scnptr;	/* file ptr to raw data for section */
+	int32_t		s_relptr;	/* file ptr to relocation */
+	int32_t		s_lnnoptr;	/* file ptr to gp histogram */
+	uint16_t	s_nreloc;	/* number of relocation entries */
+	uint16_t	s_nlnno;	/* number of gp histogram entries */
+	int32_t		s_flags;	/* flags */
+} SCNHDR;
+#define SCNHSZ		sizeof(SCNHDR)
+#define SCNROUND	((int32_t)16)
+
+typedef struct aouthdr {
+	int16_t	magic;		/* see above				*/
+	int16_t	vstamp;		/* version stamp			*/
+	int32_t	tsize;		/* text size in bytes, padded to DW bdry*/
+	int32_t	dsize;		/* initialized data "  "		*/
+	int32_t	bsize;		/* uninitialized data "	  "		*/
+	int32_t	entry;		/* entry pt.				*/
+	int32_t	text_start;	/* base of text used for this file	*/
+	int32_t	data_start;	/* base of data used for this file	*/
+	int32_t	bss_start;	/* base of bss used for this file	*/
+	int32_t	gprmask;	/* general purpose register mask	*/
+	int32_t	cprmask[4];	/* co-processor register masks		*/
+	int32_t	gp_value;	/* the gp value used for this object	*/
+} AOUTHDR;
+#define AOUTHSZ sizeof(AOUTHDR)
+
+#define OMAGIC		0407
+#define NMAGIC		0410
+#define ZMAGIC		0413
+#define SMAGIC		0411
+#define LIBMAGIC	0443
+
+#define N_TXTOFF(f, a) \
+ ((a).magic == ZMAGIC || (a).magic == LIBMAGIC ? 0 : \
+  ((a).vstamp < 23 ? \
+   ((FILHSZ + AOUTHSZ + (f).f_nscns * SCNHSZ + 7) & 0xfffffff8) : \
+   ((FILHSZ + AOUTHSZ + (f).f_nscns * SCNHSZ + SCNROUND-1) & ~(SCNROUND-1)) ) )
+#define N_DATOFF(f, a) \
+  N_TXTOFF(f, a) + (a).tsize;