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AJvYcCXMDLo+nIr8aJdZBPoOvceiYSBcYFerEs405Qt0LfGsdJH0/bzhjsQc4Amuvrb9yJmeWo6ncQ3Guao=@vger.kernel.org X-Gm-Message-State: AOJu0Yy4J0NOkGSx/+nL7db/UNhk0oFCNp9RjWVOw8ebBZ+p/ybsHQ/m 1hTKiCgHD3lz6joI9ytVSt91qnwufaPw0zs5rvfmYn7/kHMbuN7Woksz6Lxoyw3ndTPxZdPKHlC a0+v1RinfegYzGH5TxsHOYoVaOg== X-Received: from pjtf15.prod.google.com ([2002:a17:90a:c28f:b0:359:8bb2:c98d]) (user=ackerleytng job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:3e81:b0:35b:a8cf:7969 with SMTP id 98e67ed59e1d1-35c30000104mr272692a91.11.1774563878752; Thu, 26 Mar 2026 15:24:38 -0700 (PDT) Date: Thu, 26 Mar 2026 15:24:16 -0700 In-Reply-To: <20260326-gmem-inplace-conversion-v4-0-e202fe950ffd@google.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260326-gmem-inplace-conversion-v4-0-e202fe950ffd@google.com> X-Developer-Key: i=ackerleytng@google.com; a=ed25519; pk=sAZDYXdm6Iz8FHitpHeFlCMXwabodTm7p8/3/8xUxuU= X-Developer-Signature: v=1; a=ed25519-sha256; t=1774563861; l=2199; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=Bkrh8dbtdInO5wZHJbP237TumUuE8eZL80zRafq4z5c=; b=r+Ksvf5Tzi9wrZK3RvQc1ByJZ1ZJxVo8VxXv/mzOeG32ukrA+EzJbetR3GTGB2X4avA5pYEIw 2Sc+4DsfnYHB5FEh+yTsFYKnnRlz4kYJ7QAOuJpchSQEInd/x8o+zGI X-Mailer: b4 0.14.3 Message-ID: <20260326-gmem-inplace-conversion-v4-7-e202fe950ffd@google.com> Subject: [PATCH RFC v4 07/44] KVM: guest_memfd: Only prepare folios for private pages From: Ackerley Tng To: aik@amd.com, andrew.jones@linux.dev, binbin.wu@linux.intel.com, brauner@kernel.org, chao.p.peng@linux.intel.com, david@kernel.org, ira.weiny@intel.com, jmattson@google.com, jroedel@suse.de, jthoughton@google.com, michael.roth@amd.com, oupton@kernel.org, pankaj.gupta@amd.com, qperret@google.com, rick.p.edgecombe@intel.com, rientjes@google.com, shivankg@amd.com, steven.price@arm.com, tabba@google.com, willy@infradead.org, wyihan@google.com, yan.y.zhao@intel.com, forkloop@google.com, pratyush@kernel.org, suzuki.poulose@arm.com, aneesh.kumar@kernel.org, Paolo Bonzini , Sean Christopherson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Jonathan Corbet , Shuah Khan , Shuah Khan , Vishal Annapurve , Andrew Morton , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Jason Gunthorpe , Vlastimil Babka Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, Ackerley Tng Content-Type: text/plain; charset="utf-8" All-shared guest_memfd used to be only supported for non-CoCo VMs where preparation doesn't apply. INIT_SHARED is about to be supported for non-CoCo VMs in a later patch in this series. In addition, KVM_SET_MEMORY_ATTRIBUTES2 is about to be supported in guest_memfd in a later patch in this series. This means that the kvm fault handler may now call kvm_gmem_get_pfn() on a shared folio for a CoCo VM where preparation applies. Add a check to make sure that preparation is only performed for private folios. Preparation will be undone on freeing (see kvm_gmem_free_folio()) and on conversion to shared. Signed-off-by: Ackerley Tng --- virt/kvm/guest_memfd.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index b6ffa8734175d..d414ebfcb4c19 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -900,6 +900,7 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, int *max_order) { pgoff_t index = kvm_gmem_get_index(slot, gfn); + struct inode *inode; struct folio *folio; int r = 0; @@ -907,7 +908,8 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, if (!file) return -EFAULT; - filemap_invalidate_lock_shared(file_inode(file)->i_mapping); + inode = file_inode(file); + filemap_invalidate_lock_shared(inode->i_mapping); folio = __kvm_gmem_get_pfn(file, slot, index, pfn, max_order); if (IS_ERR(folio)) { @@ -920,7 +922,8 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, folio_mark_uptodate(folio); } - r = kvm_gmem_prepare_folio(kvm, slot, gfn, folio); + if (kvm_gmem_is_private_mem(inode, index)) + r = kvm_gmem_prepare_folio(kvm, slot, gfn, folio); folio_unlock(folio); @@ -930,7 +933,7 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, folio_put(folio); out: - filemap_invalidate_unlock_shared(file_inode(file)->i_mapping); + filemap_invalidate_unlock_shared(inode->i_mapping); return r; } EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_gmem_get_pfn); -- 2.53.0.1018.g2bb0e51243-goog