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/powerpc/boot/mktree.c | 151 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 151 insertions(+) create mode 100644 arch/powerpc/boot/mktree.c (limited to 'arch/powerpc/boot/mktree.c') diff --git a/arch/powerpc/boot/mktree.c b/arch/powerpc/boot/mktree.c new file mode 100644 index 000000000..dc603f3c1 --- /dev/null +++ b/arch/powerpc/boot/mktree.c @@ -0,0 +1,151 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Makes a tree bootable image for IBM Evaluation boards. + * Basically, just take a zImage, skip the ELF header, and stuff + * a 32 byte header on the front. + * + * We use htonl, which is a network macro, to make sure we're doing + * The Right Thing on an LE machine. It's non-obvious, but it should + * work on anything BSD'ish. + */ + +#include +#include +#include +#include +#include +#include +#include +#ifdef __sun__ +#include +#else +#include +#endif + +/* This gets tacked on the front of the image. There are also a few + * bytes allocated after the _start label used by the boot rom (see + * head.S for details). + */ +typedef struct boot_block { + uint32_t bb_magic; /* 0x0052504F */ + uint32_t bb_dest; /* Target address of the image */ + uint32_t bb_num_512blocks; /* Size, rounded-up, in 512 byte blks */ + uint32_t bb_debug_flag; /* Run debugger or image after load */ + uint32_t bb_entry_point; /* The image address to start */ + uint32_t bb_checksum; /* 32 bit checksum including header */ + uint32_t reserved[2]; +} boot_block_t; + +#define IMGBLK 512 +unsigned int tmpbuf[IMGBLK / sizeof(unsigned int)]; + +int main(int argc, char *argv[]) +{ + int in_fd, out_fd; + int nblks, i; + unsigned int cksum, *cp; + struct stat st; + boot_block_t bt; + + if (argc < 5) { + fprintf(stderr, "usage: %s \n",argv[0]); + exit(1); + } + + if (stat(argv[1], &st) < 0) { + perror("stat"); + exit(2); + } + + nblks = (st.st_size + IMGBLK) / IMGBLK; + + bt.bb_magic = htonl(0x0052504F); + + /* If we have the optional entry point parameter, use it */ + bt.bb_dest = htonl(strtoul(argv[3], NULL, 0)); + bt.bb_entry_point = htonl(strtoul(argv[4], NULL, 0)); + + /* We know these from the linker command. + * ...and then move it up into memory a little more so the + * relocation can happen. + */ + bt.bb_num_512blocks = htonl(nblks); + bt.bb_debug_flag = 0; + + bt.bb_checksum = 0; + + /* To be neat and tidy :-). + */ + bt.reserved[0] = 0; + bt.reserved[1] = 0; + + if ((in_fd = open(argv[1], O_RDONLY)) < 0) { + perror("zImage open"); + exit(3); + } + + if ((out_fd = open(argv[2], (O_RDWR | O_CREAT | O_TRUNC), 0666)) < 0) { + perror("bootfile open"); + exit(3); + } + + cksum = 0; + cp = (void *)&bt; + for (i = 0; i < sizeof(bt) / sizeof(unsigned int); i++) + cksum += *cp++; + + /* Assume zImage is an ELF file, and skip the 64K header. + */ + if (read(in_fd, tmpbuf, sizeof(tmpbuf)) != sizeof(tmpbuf)) { + fprintf(stderr, "%s is too small to be an ELF image\n", + argv[1]); + exit(4); + } + + if (tmpbuf[0] != htonl(0x7f454c46)) { + fprintf(stderr, "%s is not an ELF image\n", argv[1]); + exit(4); + } + + if (lseek(in_fd, (64 * 1024), SEEK_SET) < 0) { + fprintf(stderr, "%s failed to seek in ELF image\n", argv[1]); + exit(4); + } + + nblks -= (64 * 1024) / IMGBLK; + + /* And away we go...... + */ + if (write(out_fd, &bt, sizeof(bt)) != sizeof(bt)) { + perror("boot-image write"); + exit(5); + } + + while (nblks-- > 0) { + if (read(in_fd, tmpbuf, sizeof(tmpbuf)) < 0) { + perror("zImage read"); + exit(5); + } + cp = tmpbuf; + for (i = 0; i < sizeof(tmpbuf) / sizeof(unsigned int); i++) + cksum += *cp++; + if (write(out_fd, tmpbuf, sizeof(tmpbuf)) != sizeof(tmpbuf)) { + perror("boot-image write"); + exit(5); + } + } + + /* rewrite the header with the computed checksum. + */ + bt.bb_checksum = htonl(cksum); + if (lseek(out_fd, 0, SEEK_SET) < 0) { + perror("rewrite seek"); + exit(1); + } + if (write(out_fd, &bt, sizeof(bt)) != sizeof(bt)) { + perror("boot-image rewrite"); + exit(1); + } + + exit(0); +} -- cgit v1.3.1