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 --- io_uring/advise.c | 108 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 108 insertions(+) create mode 100644 io_uring/advise.c (limited to 'io_uring/advise.c') diff --git a/io_uring/advise.c b/io_uring/advise.c new file mode 100644 index 000000000..0073f74e3 --- /dev/null +++ b/io_uring/advise.c @@ -0,0 +1,108 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include + +#include "io_uring.h" +#include "advise.h" + +struct io_fadvise { + struct file *file; + u64 offset; + u64 len; + u32 advice; +}; + +struct io_madvise { + struct file *file; + u64 addr; + u64 len; + u32 advice; +}; + +int io_madvise_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ +#if defined(CONFIG_ADVISE_SYSCALLS) && defined(CONFIG_MMU) + struct io_madvise *ma = io_kiocb_to_cmd(req, struct io_madvise); + + if (sqe->buf_index || sqe->splice_fd_in) + return -EINVAL; + + ma->addr = READ_ONCE(sqe->addr); + ma->len = READ_ONCE(sqe->off); + if (!ma->len) + ma->len = READ_ONCE(sqe->len); + ma->advice = READ_ONCE(sqe->fadvise_advice); + req->flags |= REQ_F_FORCE_ASYNC; + return 0; +#else + return -EOPNOTSUPP; +#endif +} + +int io_madvise(struct io_kiocb *req, unsigned int issue_flags) +{ +#if defined(CONFIG_ADVISE_SYSCALLS) && defined(CONFIG_MMU) + struct io_madvise *ma = io_kiocb_to_cmd(req, struct io_madvise); + int ret; + + WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK); + + ret = do_madvise(current->mm, ma->addr, ma->len, ma->advice); + io_req_set_res(req, ret, 0); + return IOU_COMPLETE; +#else + return -EOPNOTSUPP; +#endif +} + +static bool io_fadvise_force_async(struct io_fadvise *fa) +{ + switch (fa->advice) { + case POSIX_FADV_NORMAL: + case POSIX_FADV_RANDOM: + case POSIX_FADV_SEQUENTIAL: + return false; + default: + return true; + } +} + +int io_fadvise_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + struct io_fadvise *fa = io_kiocb_to_cmd(req, struct io_fadvise); + + if (sqe->buf_index || sqe->splice_fd_in) + return -EINVAL; + + fa->offset = READ_ONCE(sqe->off); + fa->len = READ_ONCE(sqe->addr); + if (!fa->len) + fa->len = READ_ONCE(sqe->len); + fa->advice = READ_ONCE(sqe->fadvise_advice); + if (io_fadvise_force_async(fa)) + req->flags |= REQ_F_FORCE_ASYNC; + return 0; +} + +int io_fadvise(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_fadvise *fa = io_kiocb_to_cmd(req, struct io_fadvise); + int ret; + + WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK && io_fadvise_force_async(fa)); + + ret = vfs_fadvise(req->file, fa->offset, fa->len, fa->advice); + if (ret < 0) + req_set_fail(req); + io_req_set_res(req, ret, 0); + return IOU_COMPLETE; +} -- cgit v1.3.1