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 --- drivers/mtd/tests/readtest.c | 215 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 215 insertions(+) create mode 100644 drivers/mtd/tests/readtest.c (limited to 'drivers/mtd/tests/readtest.c') diff --git a/drivers/mtd/tests/readtest.c b/drivers/mtd/tests/readtest.c new file mode 100644 index 000000000..99670ef91 --- /dev/null +++ b/drivers/mtd/tests/readtest.c @@ -0,0 +1,215 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2006-2008 Nokia Corporation + * + * Check MTD device read. + * + * Author: Adrian Hunter + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include +#include +#include +#include +#include + +#include "mtd_test.h" + +static int dev = -EINVAL; +module_param(dev, int, S_IRUGO); +MODULE_PARM_DESC(dev, "MTD device number to use"); + +static struct mtd_info *mtd; +static unsigned char *iobuf; +static unsigned char *iobuf1; +static unsigned char *bbt; + +static int pgsize; +static int ebcnt; +static int pgcnt; + +static int read_eraseblock_by_page(int ebnum) +{ + int i, ret, err = 0; + loff_t addr = (loff_t)ebnum * mtd->erasesize; + void *buf = iobuf; + void *oobbuf = iobuf1; + + for (i = 0; i < pgcnt; i++) { + memset(buf, 0 , pgsize); + ret = mtdtest_read(mtd, addr, pgsize, buf); + if (ret) { + if (!err) + err = ret; + } + if (mtd->oobsize) { + struct mtd_oob_ops ops = { }; + + ops.mode = MTD_OPS_PLACE_OOB; + ops.len = 0; + ops.retlen = 0; + ops.ooblen = mtd->oobsize; + ops.oobretlen = 0; + ops.ooboffs = 0; + ops.datbuf = NULL; + ops.oobbuf = oobbuf; + ret = mtd_read_oob(mtd, addr, &ops); + if ((ret && !mtd_is_bitflip(ret)) || + ops.oobretlen != mtd->oobsize) { + pr_err("error: read oob failed at " + "%#llx\n", (long long)addr); + if (!err) + err = ret; + if (!err) + err = -EINVAL; + } + oobbuf += mtd->oobsize; + } + addr += pgsize; + buf += pgsize; + } + + return err; +} + +static void dump_eraseblock(int ebnum) +{ + int i, j, n; + char line[128]; + int pg, oob; + + pr_info("dumping eraseblock %d\n", ebnum); + n = mtd->erasesize; + for (i = 0; i < n;) { + char *p = line; + + p += sprintf(p, "%05x: ", i); + for (j = 0; j < 32 && i < n; j++, i++) + p += sprintf(p, "%02x", (unsigned int)iobuf[i]); + printk(KERN_CRIT "%s\n", line); + cond_resched(); + } + if (!mtd->oobsize) + return; + pr_info("dumping oob from eraseblock %d\n", ebnum); + n = mtd->oobsize; + for (pg = 0, i = 0; pg < pgcnt; pg++) + for (oob = 0; oob < n;) { + char *p = line; + + p += sprintf(p, "%05x: ", i); + for (j = 0; j < 32 && oob < n; j++, oob++, i++) + p += sprintf(p, "%02x", + (unsigned int)iobuf1[i]); + printk(KERN_CRIT "%s\n", line); + cond_resched(); + } +} + +static int __init mtd_readtest_init(void) +{ + uint64_t tmp; + int err, i; + + printk(KERN_INFO "\n"); + printk(KERN_INFO "=================================================\n"); + + if (dev < 0) { + pr_info("Please specify a valid mtd-device via module parameter\n"); + return -EINVAL; + } + + pr_info("MTD device: %d\n", dev); + + mtd = get_mtd_device(NULL, dev); + if (IS_ERR(mtd)) { + err = PTR_ERR(mtd); + pr_err("error: Cannot get MTD device\n"); + return err; + } + + if (mtd->writesize == 1) { + pr_info("not NAND flash, assume page size is 512 " + "bytes.\n"); + pgsize = 512; + } else + pgsize = mtd->writesize; + + tmp = mtd->size; + do_div(tmp, mtd->erasesize); + ebcnt = tmp; + pgcnt = mtd->erasesize / pgsize; + + pr_info("MTD device size %llu, eraseblock size %u, " + "page size %u, count of eraseblocks %u, pages per " + "eraseblock %u, OOB size %u\n", + (unsigned long long)mtd->size, mtd->erasesize, + pgsize, ebcnt, pgcnt, mtd->oobsize); + + err = -ENOMEM; + iobuf = kmalloc(mtd->erasesize, GFP_KERNEL); + if (!iobuf) + goto out; + iobuf1 = kmalloc(mtd->erasesize, GFP_KERNEL); + if (!iobuf1) + goto out; + + bbt = kzalloc(ebcnt, GFP_KERNEL); + if (!bbt) + goto out; + err = mtdtest_scan_for_bad_eraseblocks(mtd, bbt, 0, ebcnt); + if (err) + goto out; + + /* Read all eraseblocks 1 page at a time */ + pr_info("testing page read\n"); + for (i = 0; i < ebcnt; ++i) { + int ret; + + if (bbt[i]) + continue; + ret = read_eraseblock_by_page(i); + if (ret) { + dump_eraseblock(i); + if (!err) + err = ret; + } + + ret = mtdtest_relax(); + if (ret) { + err = ret; + goto out; + } + } + + if (err) + pr_info("finished with errors\n"); + else + pr_info("finished\n"); + +out: + + kfree(iobuf); + kfree(iobuf1); + kfree(bbt); + put_mtd_device(mtd); + if (err) + pr_info("error %d occurred\n", err); + printk(KERN_INFO "=================================================\n"); + return err; +} +module_init(mtd_readtest_init); + +static void __exit mtd_readtest_exit(void) +{ + return; +} +module_exit(mtd_readtest_exit); + +MODULE_DESCRIPTION("Read test module"); +MODULE_AUTHOR("Adrian Hunter"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1