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charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260830-gmem-inplace-conversion-v12-20-85e5fd25252a@google.com> References: <20260830-gmem-inplace-conversion-v12-0-85e5fd25252a@google.com> In-Reply-To: <20260830-gmem-inplace-conversion-v12-0-85e5fd25252a@google.com> 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, jmattson@google.com, 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, 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, liam@infradead.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 , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Youngjun Park , Qi Zheng , Shakeel Butt , Kiryl Shutsemau , Baoquan He , Jason Gunthorpe , John Hubbard , Peter Xu , tarunsahu@google.com, Randy Dunlap , Lorenzo Stoakes , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jason Gunthorpe , Fuad Tabba , Vlastimil Babka , Baoquan He 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, linux-coco@lists.linux.dev, Ackerley Tng X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1788135915; l=5596; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=wPi3PLQGrKXDeuAU5z9J7AGBTrQFd9B/lpdUMyrGDEE=; b=9k/bLEF3An1XBhsojLn0UeoSCr6PDB828IGyADWhdI3CcerN0zYcgRaFKrrd+pDMI6fEmwe7e Jh0JJIyXJ9DDWGXI4dES9EK0noyDEDN1Lyspx/TT+yisOfiYEXsItsu X-Developer-Key: i=ackerleytng@google.com; a=ed25519; pk=sAZDYXdm6Iz8FHitpHeFlCMXwabodTm7p8/3/8xUxuU= X-Endpoint-Received: by B4 Relay for ackerleytng@google.com/20260225 with auth_id=649 X-Original-From: Ackerley Tng Reply-To: ackerleytng@google.com X-Stat-Signature: noj1pnysxrwf58nagtrk61s3q6uxhsrd X-Rspamd-Queue-Id: 6537220002 X-Rspamd-Server: rspam02 X-Rspam-User: X-HE-Tag: 1788135930-749789 X-HE-Meta: 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 le9Zqvfa eimfvKtkg2LemnqRSLBUna7FpcLWdNjCRvP8685QGIbeOzZfWiDIiRPdpUjj8J7Q0D7h0gyXrWL+E9oOKWKtEgf8tdgJi/6stPr+K4w6nI0+VM01WB+KYS4Ozhk/buMCbcStr6uk1xC+pEKI5IDvIFwK3U/lXODVoY1Qx82u90LK2BYMzfP4V8V3RwGPCoW42p+ZqBzxK5yE1h8ZubxVrKqkgPJ+GQH8JzGyw8xdGjWhTDrSBHIMh0Ggw15N4ogxHvVQswM1zATEAWZC7CJZ+Jubov/vVMcInSS7xuy/69e0mZDNi8JXLoRPTenCLtbqdXwwIAAHpyUmoLBdt3D7vH+zKuqJ2cIU7jm2mRW/EDO7ziWRjFuoBPvHU275U6L093DEwUEvFPZhLwiDHkiwBcl8UHPCqzAp3jSoB0LmtZwF7ibZoj9mlwWoYWrJb2xNBm+4hSBdqWfP6dXKkLrtZzFHBgsoIbDPwabsf90QXSKUwTNia8kB0QFv4Icaz9qto42qDCheU4vKmgynf/bo5mudlag== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Michael Roth Make the source page for populating an SNP guest_memfd instance optional if in-place conversion/population is enabled. If KVM can convert the page in-place, then it's possible for guest memory to be initialized directly from userspace by mmap()'ing the guest_memfd and writing to it while the corresponding GPA ranges are in a 'shared' state, before converting them to the 'private' state expected by KVM_SEV_SNP_LAUNCH_UPDATE. Update the handling/documentation for KVM_SEV_SNP_LAUNCH_UPDATE to allow for 'uaddr' to be set to NULL when in-place conversion is enabled, which SNP_LAUNCH_UPDATE will then use to determine when it should/shouldn't copy in data from a separate memory location. Continue to enforce non-NULL when PRIVATE is tracked per-VM, not per-guest_memfd. Signed-off-by: Michael Roth [Moved condition to snp_launch_update] Signed-off-by: Sean Christopherson Tested-by: Shivank Garg Signed-off-by: Ackerley Tng --- Documentation/virt/kvm/x86/amd-memory-encryption.rst | 14 ++++++++++---- arch/x86/kvm/svm/sev.c | 11 ++++++----- virt/kvm/kvm_main.c | 1 + 3 files changed, 17 insertions(+), 9 deletions(-) diff --git a/Documentation/virt/kvm/x86/amd-memory-encryption.rst b/Documentation/virt/kvm/x86/amd-memory-encryption.rst index bd04a908a8dbd..5977fbe33b98c 100644 --- a/Documentation/virt/kvm/x86/amd-memory-encryption.rst +++ b/Documentation/virt/kvm/x86/amd-memory-encryption.rst @@ -503,7 +503,8 @@ secrets. It is required that the GPA ranges initialized by this command have had the KVM_MEMORY_ATTRIBUTE_PRIVATE attribute set in advance. See the documentation -for KVM_SET_MEMORY_ATTRIBUTES for more details on this aspect. +for KVM_SET_MEMORY_ATTRIBUTES/KVM_SET_MEMORY_ATTRIBUTES2 for more details on +this aspect. Upon success, this command is not guaranteed to have processed the entire range requested. Instead, the ``gfn_start``, ``uaddr``, and ``len`` fields of @@ -511,9 +512,14 @@ range requested. Instead, the ``gfn_start``, ``uaddr``, and ``len`` fields of remaining range that has yet to be processed. The caller should continue calling this command until those fields indicate the entire range has been processed, e.g. ``len`` is 0, ``gfn_start`` is equal to the last GFN in the -range plus 1, and ``uaddr`` is the last byte of the userspace-provided source -buffer address plus 1. In the case where ``type`` is KVM_SEV_SNP_PAGE_TYPE_ZERO, -``uaddr`` will be ignored completely. +range plus 1, and ``uaddr`` (if specified) is the last byte of the +userspace-provided source buffer address plus 1. + +In the case where ``type`` is KVM_SEV_SNP_PAGE_TYPE_ZERO, ``uaddr`` will be +ignored completely. For all other page types, ``uaddr`` is optional if in-place +conversion is enabled (i.e. when the data had been written directly to +guest_memfd while the page was in the shared state) and is required if in-place +conversion is disabled. Parameters (in): struct kvm_sev_snp_launch_update diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index dff684b88f153..63e8cfa9bf559 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2400,7 +2400,7 @@ static int sev_gmem_post_populate(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, */ if (ret && !snp_page_reclaim(kvm, pfn) && sev_populate_args->type == KVM_SEV_SNP_PAGE_TYPE_CPUID && - sev_populate_args->fw_error == SEV_RET_INVALID_PARAM) { + sev_populate_args->fw_error == SEV_RET_INVALID_PARAM && src_page) { void *src_vaddr = kmap_local_page(src_page); void *dst_vaddr = kmap_local_pfn(pfn); @@ -2433,8 +2433,8 @@ static int snp_launch_update(struct kvm *kvm, struct kvm_sev_cmd *argp) if (copy_from_user(¶ms, u64_to_user_ptr(argp->data), sizeof(params))) return -EFAULT; - pr_debug("%s: GFN start 0x%llx length 0x%llx type %d flags %d\n", __func__, - params.gfn_start, params.len, params.type, params.flags); + pr_debug("%s: GFN start 0x%llx length 0x%llx type %d flags %d src %llx\n", __func__, + params.gfn_start, params.len, params.type, params.flags, params.uaddr); if (!params.len || !PAGE_ALIGNED(params.len) || params.flags || (params.type != KVM_SEV_SNP_PAGE_TYPE_NORMAL && @@ -2446,7 +2446,8 @@ static int snp_launch_update(struct kvm *kvm, struct kvm_sev_cmd *argp) if (params.type == KVM_SEV_SNP_PAGE_TYPE_ZERO) src = NULL; - else if (!params.uaddr || !PAGE_ALIGNED(params.uaddr)) + else if ((!gmem_in_place_conversion && !params.uaddr) || + !PAGE_ALIGNED(params.uaddr)) return -EINVAL; else src = u64_to_user_ptr(params.uaddr); @@ -2493,7 +2494,7 @@ static int snp_launch_update(struct kvm *kvm, struct kvm_sev_cmd *argp) params.gfn_start += count; params.len -= count * PAGE_SIZE; - if (params.type != KVM_SEV_SNP_PAGE_TYPE_ZERO) + if (src && params.type != KVM_SEV_SNP_PAGE_TYPE_ZERO) params.uaddr += count * PAGE_SIZE; if (copy_to_user(u64_to_user_ptr(argp->data), ¶ms, sizeof(params))) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 1ea8198821917..05c518c9b8078 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -104,6 +104,7 @@ module_param(allow_unsafe_mappings, bool, 0444); #ifdef kvm_arch_has_private_mem bool __ro_after_init gmem_in_place_conversion = false; +EXPORT_SYMBOL_FOR_KVM_INTERNAL(gmem_in_place_conversion); #endif /* -- 2.55.0.897.gb25b4bd76c-goog