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Tue, 18 Mar 2025 09:20:59 -0700 (PDT) Date: Tue, 18 Mar 2025 16:20:45 +0000 In-Reply-To: <20250318162046.4016367-1-tabba@google.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250318162046.4016367-1-tabba@google.com> X-Mailer: git-send-email 2.49.0.rc1.451.g8f38331e32-goog Message-ID: <20250318162046.4016367-7-tabba@google.com> Subject: [PATCH v6 6/7] KVM: guest_memfd: Handle invalidation of shared memory From: Fuad Tabba To: kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org Cc: pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, seanjc@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, willy@infradead.org, akpm@linux-foundation.org, xiaoyao.li@intel.com, yilun.xu@intel.com, chao.p.peng@linux.intel.com, jarkko@kernel.org, amoorthy@google.com, dmatlack@google.com, isaku.yamahata@intel.com, mic@digikod.net, vbabka@suse.cz, vannapurve@google.com, ackerleytng@google.com, mail@maciej.szmigiero.name, david@redhat.com, michael.roth@amd.com, wei.w.wang@intel.com, liam.merwick@oracle.com, isaku.yamahata@gmail.com, kirill.shutemov@linux.intel.com, suzuki.poulose@arm.com, steven.price@arm.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_tsoni@quicinc.com, quic_svaddagi@quicinc.com, quic_cvanscha@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, catalin.marinas@arm.com, james.morse@arm.com, yuzenghui@huawei.com, oliver.upton@linux.dev, maz@kernel.org, will@kernel.org, qperret@google.com, keirf@google.com, roypat@amazon.co.uk, shuah@kernel.org, hch@infradead.org, jgg@nvidia.com, rientjes@google.com, jhubbard@nvidia.com, fvdl@google.com, hughd@google.com, jthoughton@google.com, peterx@redhat.com, tabba@google.com When guest_memfd backed memory is invalidated, e.g., on punching holes, releasing, ensure that the sharing states are updated and that any folios in a transient state are restored to an appropriate state. Signed-off-by: Fuad Tabba --- virt/kvm/guest_memfd.c | 56 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 4fd9e5760503..0487a08615f0 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -117,6 +117,16 @@ static struct folio *kvm_gmem_get_folio(struct inode *inode, pgoff_t index) return filemap_grab_folio(inode->i_mapping, index); } +#ifdef CONFIG_KVM_GMEM_SHARED_MEM +static void kvm_gmem_offset_range_invalidate_shared(struct inode *inode, + pgoff_t start, pgoff_t end); +#else +static inline void kvm_gmem_offset_range_invalidate_shared(struct inode *inode, + pgoff_t start, pgoff_t end) +{ +} +#endif + static void kvm_gmem_invalidate_begin(struct kvm_gmem *gmem, pgoff_t start, pgoff_t end) { @@ -126,6 +136,7 @@ static void kvm_gmem_invalidate_begin(struct kvm_gmem *gmem, pgoff_t start, unsigned long index; xa_for_each_range(&gmem->bindings, index, slot, start, end - 1) { + struct file *file = READ_ONCE(slot->gmem.file); pgoff_t pgoff = slot->gmem.pgoff; struct kvm_gfn_range gfn_range = { @@ -145,6 +156,16 @@ static void kvm_gmem_invalidate_begin(struct kvm_gmem *gmem, pgoff_t start, } flush |= kvm_mmu_unmap_gfn_range(kvm, &gfn_range); + + /* + * If this gets called after kvm_gmem_unbind() it means that all + * in-flight operations are gone, and the file has been closed. + */ + if (file) { + kvm_gmem_offset_range_invalidate_shared(file_inode(file), + gfn_range.start, + gfn_range.end); + } } if (flush) @@ -509,6 +530,41 @@ static int kvm_gmem_offset_clear_shared(struct inode *inode, pgoff_t index) return r; } +/* + * Callback when invalidating memory that is potentially shared. + * + * Must be called with the filemap (inode->i_mapping) invalidate_lock held. + */ +static void kvm_gmem_offset_range_invalidate_shared(struct inode *inode, + pgoff_t start, pgoff_t end) +{ + struct xarray *shared_offsets = &kvm_gmem_private(inode)->shared_offsets; + pgoff_t i; + + rwsem_assert_held_write_nolockdep(&inode->i_mapping->invalidate_lock); + + for (i = start; i < end; i++) { + /* + * If the folio is NONE_SHARED, it indicates that it is + * transitioning to private (GUEST_SHARED). Transition it to + * shared (ALL_SHARED) and remove the callback. + */ + if (xa_to_value(xa_load(shared_offsets, i)) == KVM_GMEM_NONE_SHARED) { + struct folio *folio = folio = filemap_lock_folio(inode->i_mapping, i); + + if (!WARN_ON_ONCE(IS_ERR(folio))) { + if (folio_test_guestmem(folio)) + kvm_gmem_restore_pending_folio(folio, inode); + + folio_unlock(folio); + folio_put(folio); + } + } + + xa_erase(shared_offsets, i); + } +} + /* * Marks the range [start, end) as not shared with the host. If the host doesn't * have any references to a particular folio, then that folio is marked as