From: Sean Christopherson <seanjc@google.com>
To: Binbin Wu <binbin.wu@linux.intel.com>
Cc: Marc Zyngier <maz@kernel.org>,
Oliver Upton <oliver.upton@linux.dev>,
Tianrui Zhao <zhaotianrui@loongson.cn>,
Bibo Mao <maobibo@loongson.cn>,
Huacai Chen <chenhuacai@kernel.org>,
Madhavan Srinivasan <maddy@linux.ibm.com>,
Anup Patel <anup@brainfault.org>, Paul Walmsley <pjw@kernel.org>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Paolo Bonzini <pbonzini@redhat.com>,
"Kirill A. Shutemov" <kas@kernel.org>,
linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
kvm@vger.kernel.org, loongarch@lists.linux.dev,
linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org,
x86@kernel.org, linux-coco@lists.linux.dev,
linux-kernel@vger.kernel.org, Ira Weiny <ira.weiny@intel.com>,
Kai Huang <kai.huang@intel.com>,
Michael Roth <michael.roth@amd.com>,
Yan Zhao <yan.y.zhao@intel.com>,
Vishal Annapurve <vannapurve@google.com>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
Ackerley Tng <ackerleytng@google.com>
Subject: Re: [PATCH v4 27/28] KVM: TDX: Bug the VM if extending the initial measurement fails
Date: Tue, 4 Nov 2025 10:02:26 -0800 [thread overview]
Message-ID: <aQo_spywQuek7fUi@google.com> (raw)
In-Reply-To: <31da959f-d004-4ae0-a6a7-d5d31b646b70@linux.intel.com>
On Tue, Nov 04, 2025, Binbin Wu wrote:
>
>
> On 10/31/2025 4:09 AM, Sean Christopherson wrote:
> > WARN and terminate the VM if TDH_MR_EXTEND fails, as extending the
> > measurement should fail if and only if there is a KVM bug, or if the S-EPT
> > mapping is invalid. Now that KVM makes all state transitions mutually
> > exclusive via tdx_vm_state_guard, it should be impossible for S-EPT
> > mappings to be removed between kvm_tdp_mmu_map_private_pfn() and
> > tdh_mr_extend().
> >
> > Holding slots_lock prevents zaps due to memslot updates,
> > filemap_invalidate_lock() prevents zaps due to guest_memfd PUNCH_HOLE,
> > vcpu->mutex locks prevents updates from other vCPUs, kvm->lock prevents
> > VM-scoped ioctls from creating havoc (e.g. by creating new vCPUs), and all
> > usage of kvm_zap_gfn_range() is mutually exclusive with S-EPT entries that
> > can be used for the initial image.
> >
> > For kvm_zap_gfn_range(), the call from sev.c is obviously mutually
> > exclusive, TDX disallows KVM_X86_QUIRK_IGNORE_GUEST_PAT so the same goes
> > for kvm_noncoherent_dma_assignment_start_or_stop(), and
> > __kvm_set_or_clear_apicv_inhibit() is blocked by virtue of holding all
> > VM and vCPU mutexes (and the APIC page has its own non-guest_memfd memslot
>
> Nit:
> It sounds like TDX is using the memslot for the APIC page, but for a TD, the
> memslot for the APIC page is never initialized or used?
Oh! Good point. I'll tweak that snippet when applying.
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next prev parent reply other threads:[~2025-11-04 18:02 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-30 20:09 [PATCH v4 00/28] KVM: x86/mmu: TDX post-populate cleanups Sean Christopherson
2025-10-30 20:09 ` [PATCH v4 01/28] KVM: Make support for kvm_arch_vcpu_async_ioctl() mandatory Sean Christopherson
2025-10-30 20:09 ` [PATCH v4 02/28] KVM: Rename kvm_arch_vcpu_async_ioctl() to kvm_arch_vcpu_unlocked_ioctl() Sean Christopherson
2025-10-30 20:09 ` [PATCH v4 03/28] KVM: TDX: Drop PROVE_MMU=y sanity check on to-be-populated mappings Sean Christopherson
2025-10-30 20:09 ` [PATCH v4 04/28] KVM: x86/mmu: Add dedicated API to map guest_memfd pfn into TDP MMU Sean Christopherson
2025-10-31 7:58 ` Binbin Wu
2025-10-30 20:09 ` [PATCH v4 05/28] KVM: x86/mmu: WARN if KVM attempts to map into an invalid TDP MMU root Sean Christopherson
2025-10-30 22:17 ` Huang, Kai
2025-10-30 20:09 ` [PATCH v4 06/28] Revert "KVM: x86/tdp_mmu: Add a helper function to walk down the TDP MMU" Sean Christopherson
2025-10-30 20:09 ` [PATCH v4 07/28] KVM: x86/mmu: Rename kvm_tdp_map_page() to kvm_tdp_page_prefault() Sean Christopherson
2025-10-30 20:09 ` [PATCH v4 08/28] KVM: TDX: Drop superfluous page pinning in S-EPT management Sean Christopherson
2025-10-31 8:29 ` Yan Zhao
2025-10-31 17:12 ` Sean Christopherson
2025-10-30 20:09 ` [PATCH v4 09/28] KVM: TDX: Return -EIO, not -EINVAL, on a KVM_BUG_ON() condition Sean Christopherson
2025-10-30 22:20 ` Huang, Kai
2025-10-30 20:09 ` [PATCH v4 10/28] KVM: TDX: Fold tdx_sept_drop_private_spte() into tdx_sept_remove_private_spte() Sean Christopherson
2025-10-31 8:23 ` Yan Zhao
2025-10-30 20:09 ` [PATCH v4 11/28] KVM: x86/mmu: Drop the return code from kvm_x86_ops.remove_external_spte() Sean Christopherson
2025-10-30 22:26 ` Huang, Kai
2025-10-30 20:09 ` [PATCH v4 12/28] KVM: TDX: WARN if mirror SPTE doesn't have full RWX when creating S-EPT mapping Sean Christopherson
2025-10-30 22:59 ` Huang, Kai
2025-10-30 23:40 ` Sean Christopherson
2025-10-30 23:59 ` Huang, Kai
2025-10-31 8:19 ` Binbin Wu
2025-10-30 20:09 ` [PATCH v4 13/28] KVM: TDX: Avoid a double-KVM_BUG_ON() in tdx_sept_zap_private_spte() Sean Christopherson
2025-10-30 20:09 ` [PATCH v4 14/28] KVM: TDX: Use atomic64_dec_return() instead of a poor equivalent Sean Christopherson
2025-10-30 20:09 ` [PATCH v4 15/28] KVM: TDX: Fold tdx_mem_page_record_premap_cnt() into its sole caller Sean Christopherson
2025-10-30 20:09 ` [PATCH v4 16/28] KVM: TDX: ADD pages to the TD image while populating mirror EPT entries Sean Christopherson
2025-10-31 8:54 ` Binbin Wu
2025-10-30 20:09 ` [PATCH v4 17/28] KVM: TDX: Fold tdx_sept_zap_private_spte() into tdx_sept_remove_private_spte() Sean Christopherson
2025-10-31 8:56 ` Binbin Wu
2025-10-30 20:09 ` [PATCH v4 18/28] KVM: TDX: Combine KVM_BUG_ON + pr_tdx_error() into TDX_BUG_ON() Sean Christopherson
2025-10-30 23:20 ` Huang, Kai
2025-10-31 8:58 ` Binbin Wu
2025-10-30 20:09 ` [PATCH v4 19/28] KVM: TDX: Derive error argument names from the local variable names Sean Christopherson
2025-10-31 9:00 ` Binbin Wu
2025-10-30 20:09 ` [PATCH v4 20/28] KVM: TDX: Assert that mmu_lock is held for write when removing S-EPT entries Sean Christopherson
2025-10-30 23:03 ` Huang, Kai
2025-10-31 9:05 ` Binbin Wu
2025-10-30 20:09 ` [PATCH v4 21/28] KVM: TDX: Add macro to retry SEAMCALLs when forcing vCPUs out of guest Sean Christopherson
2025-10-30 23:05 ` Huang, Kai
2025-10-31 9:08 ` Binbin Wu
2025-10-30 20:09 ` [PATCH v4 22/28] KVM: TDX: Add tdx_get_cmd() helper to get and validate sub-ioctl command Sean Christopherson
2025-10-31 9:11 ` Binbin Wu
2025-10-30 20:09 ` [PATCH v4 23/28] KVM: TDX: Convert INIT_MEM_REGION and INIT_VCPU to "unlocked" vCPU ioctl Sean Christopherson
2025-10-31 9:15 ` Binbin Wu
2025-10-30 20:09 ` [PATCH v4 24/28] KVM: TDX: Use guard() to acquire kvm->lock in tdx_vm_ioctl() Sean Christopherson
2025-10-31 9:17 ` Binbin Wu
2025-10-30 20:09 ` [PATCH v4 25/28] KVM: TDX: Don't copy "cmd" back to userspace for KVM_TDX_CAPABILITIES Sean Christopherson
2025-10-30 23:06 ` Huang, Kai
2025-10-30 20:09 ` [PATCH v4 26/28] KVM: TDX: Guard VM state transitions with "all" the locks Sean Christopherson
2025-10-30 23:08 ` Huang, Kai
2025-10-31 8:26 ` Yan Zhao
2025-10-31 17:34 ` Sean Christopherson
2025-11-03 1:36 ` Yan Zhao
2025-10-30 20:09 ` [PATCH v4 27/28] KVM: TDX: Bug the VM if extending the initial measurement fails Sean Christopherson
2025-10-30 23:09 ` Huang, Kai
2025-11-04 6:16 ` Binbin Wu
2025-11-04 18:02 ` Sean Christopherson [this message]
2025-10-30 20:09 ` [PATCH v4 28/28] KVM: TDX: Fix list_add corruption during vcpu_load() Sean Christopherson
2025-10-30 23:12 ` Huang, Kai
2025-10-30 23:19 ` [PATCH v4 00/28] KVM: x86/mmu: TDX post-populate cleanups Huang, Kai
2025-10-31 8:54 ` Yan Zhao
2025-10-31 17:28 ` Edgecombe, Rick P
2025-11-04 17:58 ` Sean Christopherson
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