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a=ed25519-sha256; t=1774563861; l=3333; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=+lH9JgLOF707IWKJRbslu6RR2YV0S99MONEW8Yc3BZ8=; b=M/Gbb884LE5QPF+3EzZzuqSIO6Odv8JZWUawyA7Mhz//bCISt9epGhctguzMXhMlD/ZE6w0Rj EGaXkNBVodNBXGot/DtKS79CF61Z84KbG7KljbyQM3ZQboU3Sv7s68x X-Mailer: b4 0.14.3 Message-ID: <20260326-gmem-inplace-conversion-v4-14-e202fe950ffd@google.com> Subject: [PATCH RFC v4 14/44] KVM: x86: Add support for applying content modes 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" Content-Transfer-Encoding: quoted-printable For x86, override the default implementations of content mode functions to handle reporting of supported content modes, and application of requested modes based on x86 VM types. Signed-off-by: Ackerley Tng --- arch/x86/kvm/x86.c | 101 +++++++++++++++++++++++++++++++++++++++++++++++++= ++++ 1 file changed, 101 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 9c29407712580..3bbc8ffbf489e 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -14078,6 +14078,107 @@ void kvm_arch_gmem_invalidate(kvm_pfn_t start, kv= m_pfn_t end) kvm_x86_call(gmem_invalidate)(start, end); } #endif + +u64 kvm_arch_gmem_supported_content_modes(struct kvm *kvm) +{ + switch (kvm->arch.vm_type) { + case KVM_X86_SW_PROTECTED_VM: + return KVM_SET_MEMORY_ATTRIBUTES2_ZERO | + KVM_SET_MEMORY_ATTRIBUTES2_PRESERVE; + case KVM_X86_SNP_VM: + case KVM_X86_TDX_VM: + return KVM_SET_MEMORY_ATTRIBUTES2_ZERO; + default: + return 0; + } +} + +int kvm_arch_gmem_apply_content_mode_zero(struct kvm *kvm, struct inode *i= node, + pgoff_t start, pgoff_t end) +{ + switch (kvm->arch.vm_type) { + case KVM_X86_SW_PROTECTED_VM: + case KVM_X86_SNP_VM: + case KVM_X86_TDX_VM: + /* + * TDX firmware will zero on unmapping from the + * Secure-EPTs, but suppose a shared page with + * contents was converted to private, and then + * converted back without ever being mapped into + * Secure-EPTs: guest_memfd can't rely on TDX firmware + * for zeroing then. + */ + return kvm_gmem_apply_content_mode_zero(inode, start, end); + default: + WARN_ONCE(1, "Unexpected request to zero for vm_type."); + return -EOPNOTSUPP; + } +} + +int kvm_arch_gmem_apply_content_mode_preserve(struct kvm *kvm, + struct inode *inode, + pgoff_t start, pgoff_t end) +{ + switch (kvm->arch.vm_type) { + case KVM_X86_SW_PROTECTED_VM: + return 0; + default: + WARN_ONCE(1, "Unexpected request to preserve for vm_type."); + return -EOPNOTSUPP; + } +} + +static int __scramble_range(struct inode *inode, pgoff_t start, pgoff_t en= d) +{ + struct address_space *mapping =3D inode->i_mapping; + struct folio_batch fbatch; + struct folio *f; + char *kaddr; + int ret =3D 0; + int i; + + folio_batch_init(&fbatch); + while (!ret && filemap_get_folios(mapping, &start, end - 1, &fbatch)) { + for (i =3D 0; !ret && i < folio_batch_count(&fbatch); ++i) { + f =3D fbatch.folios[i]; + + folio_lock(f); + + if (folio_test_hwpoison(f)) { + ret =3D -EHWPOISON; + } else { + /* + * Hard-coding range to scramble since + * guest_memfd only supports PAGE_SIZE + * folios now. + */ + kaddr =3D kmap_local_folio(f, 0); + get_random_bytes(kaddr, PAGE_SIZE); + kunmap_local(kaddr); + } + + folio_unlock(f); + } + + folio_batch_release(&fbatch); + cond_resched(); + } + + return ret; +} + +int kvm_arch_gmem_apply_content_mode_unspecified(struct kvm *kvm, + struct inode *inode, + pgoff_t start, pgoff_t end) +{ + switch (kvm->arch.vm_type) { + case KVM_X86_SW_PROTECTED_VM: + return __scramble_range(inode, start, end); + default: + return 0; + } +} + #endif =20 int kvm_spec_ctrl_test_value(u64 value) --=20 2.53.0.1018.g2bb0e51243-goog