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 --- fs/nfs/getroot.c | 133 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 133 insertions(+) create mode 100644 fs/nfs/getroot.c (limited to 'fs/nfs/getroot.c') diff --git a/fs/nfs/getroot.c b/fs/nfs/getroot.c new file mode 100644 index 000000000..ff7424bc4 --- /dev/null +++ b/fs/nfs/getroot.c @@ -0,0 +1,133 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* getroot.c: get the root dentry for an NFS mount + * + * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include +#include + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +#include "internal.h" + +#define NFSDBG_FACILITY NFSDBG_CLIENT + +/* + * get a root dentry from the root filehandle + */ +int nfs_get_root(struct super_block *s, struct fs_context *fc) +{ + struct nfs_fs_context *ctx = nfs_fc2context(fc); + struct nfs_server *server = NFS_SB(s), *clone_server; + struct nfs_fsinfo fsinfo; + struct dentry *root; + struct inode *inode; + char *name; + int error = -ENOMEM; + unsigned long kflags = 0, kflags_out = 0; + + name = kstrdup(fc->source, GFP_KERNEL); + if (!name) + goto out; + + /* get the actual root for this mount */ + fsinfo.fattr = nfs_alloc_fattr_with_label(server); + if (fsinfo.fattr == NULL) + goto out_name; + + error = server->nfs_client->rpc_ops->getroot(server, ctx->mntfh, &fsinfo); + if (error < 0) { + dprintk("nfs_get_root: getattr error = %d\n", -error); + nfs_errorf(fc, "NFS: Couldn't getattr on root"); + goto out_fattr; + } + + inode = nfs_fhget(s, ctx->mntfh, fsinfo.fattr); + if (IS_ERR(inode)) { + dprintk("nfs_get_root: get root inode failed\n"); + error = PTR_ERR(inode); + nfs_errorf(fc, "NFS: Couldn't get root inode"); + goto out_fattr; + } + + /* root dentries normally start off anonymous and get spliced in later + * if the dentry tree reaches them; however if the dentry already + * exists, we'll pick it up at this point and use it as the root + */ + root = d_obtain_root(inode); + if (IS_ERR(root)) { + dprintk("nfs_get_root: get root dentry failed\n"); + error = PTR_ERR(root); + nfs_errorf(fc, "NFS: Couldn't get root dentry"); + goto out_fattr; + } + + security_d_instantiate(root, inode); + spin_lock(&root->d_lock); + if (IS_ROOT(root) && !root->d_fsdata && + !(root->d_flags & DCACHE_NFSFS_RENAMED)) { + root->d_fsdata = name; + name = NULL; + } + spin_unlock(&root->d_lock); + if (!s->s_root) + s->s_root = dget(root); + fc->root = root; + if (server->caps & NFS_CAP_SECURITY_LABEL) + kflags |= SECURITY_LSM_NATIVE_LABELS; + if (ctx->clone_data.sb) { + if (d_inode(fc->root)->i_fop != &nfs_dir_operations) { + error = -ESTALE; + goto error_splat_root; + } + /* clone lsm security options from the parent to the new sb */ + error = security_sb_clone_mnt_opts(ctx->clone_data.sb, + s, kflags, &kflags_out); + if (error) + goto error_splat_root; + clone_server = NFS_SB(ctx->clone_data.sb); + server->has_sec_mnt_opts = clone_server->has_sec_mnt_opts; + } else { + error = security_sb_set_mnt_opts(s, fc->security, + kflags, &kflags_out); + } + if (error) + goto error_splat_root; + if (server->caps & NFS_CAP_SECURITY_LABEL && + !(kflags_out & SECURITY_LSM_NATIVE_LABELS)) + server->caps &= ~NFS_CAP_SECURITY_LABEL; + + nfs_setsecurity(inode, fsinfo.fattr); + error = 0; + +out_fattr: + nfs_free_fattr(fsinfo.fattr); +out_name: + kfree(name); +out: + return error; +error_splat_root: + dput(fc->root); + fc->root = NULL; + goto out_fattr; +} -- cgit v1.3.1