From 93de2a6a4b91b72607136dd656edf03fb399d27f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 23 Sep 2026 09:37:21 -0700 Subject: KVM: SEV: Do cache maintenance on the source VM during intra-host migration 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 Signed-off-by: Sean Christopherson Message-ID: <20260923163721.1584779-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/xtensa/boot/lib/.gitignore | 4 ++ arch/xtensa/boot/lib/Makefile | 34 +++++++++++++++++ arch/xtensa/boot/lib/zmem.c | 81 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 119 insertions(+) create mode 100644 arch/xtensa/boot/lib/.gitignore create mode 100644 arch/xtensa/boot/lib/Makefile create mode 100644 arch/xtensa/boot/lib/zmem.c (limited to 'arch/xtensa/boot/lib') diff --git a/arch/xtensa/boot/lib/.gitignore b/arch/xtensa/boot/lib/.gitignore new file mode 100644 index 000000000..805a82492 --- /dev/null +++ b/arch/xtensa/boot/lib/.gitignore @@ -0,0 +1,4 @@ +# SPDX-License-Identifier: GPL-2.0-only +inffast.c +inflate.c +inftrees.c diff --git a/arch/xtensa/boot/lib/Makefile b/arch/xtensa/boot/lib/Makefile new file mode 100644 index 000000000..0378a22a0 --- /dev/null +++ b/arch/xtensa/boot/lib/Makefile @@ -0,0 +1,34 @@ +# SPDX-License-Identifier: GPL-2.0 +# +# Makefile for some libs needed by zImage. +# + +zlib := inffast.c inflate.c inftrees.c + +lib-y += $(zlib:.c=.o) zmem.o + +ccflags-y := -I $(srctree)/lib/zlib_inflate +ifdef CONFIG_FUNCTION_TRACER +CFLAGS_REMOVE_inflate.o = -pg +CFLAGS_REMOVE_zmem.o = -pg +CFLAGS_REMOVE_inftrees.o = -pg +CFLAGS_REMOVE_inffast.o = -pg +endif + +KASAN_SANITIZE := n +KCSAN_SANITIZE := n +KCOV_INSTRUMENT := n +GCOV_PROFILE := n + +CFLAGS_REMOVE_inflate.o += -fstack-protector -fstack-protector-strong +CFLAGS_REMOVE_zmem.o += -fstack-protector -fstack-protector-strong +CFLAGS_REMOVE_inftrees.o += -fstack-protector -fstack-protector-strong +CFLAGS_REMOVE_inffast.o += -fstack-protector -fstack-protector-strong + +quiet_cmd_copy_zlib = COPY $@ + cmd_copy_zlib = cat $< > $@ + +$(addprefix $(obj)/,$(zlib)): $(obj)/%: $(srctree)/lib/zlib_inflate/% + $(call cmd,copy_zlib) + +clean-files := $(zlib) diff --git a/arch/xtensa/boot/lib/zmem.c b/arch/xtensa/boot/lib/zmem.c new file mode 100644 index 000000000..b89189355 --- /dev/null +++ b/arch/xtensa/boot/lib/zmem.c @@ -0,0 +1,81 @@ +// SPDX-License-Identifier: GPL-2.0 +#include + +/* bits taken from ppc */ + +extern void *avail_ram, *end_avail; +void gunzip(void *dst, int dstlen, unsigned char *src, int *lenp); + +static void exit(void) +{ + for (;;); +} + +static void *zalloc(unsigned int size) +{ + void *p = avail_ram; + + size = (size + 7) & -8; + avail_ram += size; + if (avail_ram > end_avail) { + //puts("oops... out of memory\n"); + //pause(); + exit (); + } + return p; +} + +#define HEAD_CRC 2 +#define EXTRA_FIELD 4 +#define ORIG_NAME 8 +#define COMMENT 0x10 +#define RESERVED 0xe0 + +#define DEFLATED 8 + +void gunzip (void *dst, int dstlen, unsigned char *src, int *lenp) +{ + z_stream s; + int r, i, flags; + + /* skip header */ + i = 10; + flags = src[3]; + if (src[2] != DEFLATED || (flags & RESERVED) != 0) { + //puts("bad gzipped data\n"); + exit(); + } + if ((flags & EXTRA_FIELD) != 0) + i = 12 + src[10] + (src[11] << 8); + if ((flags & ORIG_NAME) != 0) + while (src[i++] != 0) + ; + if ((flags & COMMENT) != 0) + while (src[i++] != 0) + ; + if ((flags & HEAD_CRC) != 0) + i += 2; + if (i >= *lenp) { + //puts("gunzip: ran out of data in header\n"); + exit(); + } + + s.workspace = zalloc(zlib_inflate_workspacesize()); + r = zlib_inflateInit2(&s, -MAX_WBITS); + if (r != Z_OK) { + //puts("inflateInit2 returned "); puthex(r); puts("\n"); + exit(); + } + s.next_in = src + i; + s.avail_in = *lenp - i; + s.next_out = dst; + s.avail_out = dstlen; + r = zlib_inflate(&s, Z_FINISH); + if (r != Z_OK && r != Z_STREAM_END) { + //puts("inflate returned "); puthex(r); puts("\n"); + exit(); + } + *lenp = s.next_out - (unsigned char *) dst; + zlib_inflateEnd(&s); +} + -- cgit v1.3.1