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AJvYcCXOJbOn/sQOd9Ed2Ll3q5ygc9ezVYaE2e/S+aXyg061WopXbjZyt4TYS/wppWfwXAyr8WQDlAw9o9zV@lists.linux.dev X-Gm-Message-State: AOJu0YwvpL5m7ujnG1oboCCIJDFUX3X3IcDgonlDGxGkmR6y8B3V3kI/ zdUytjxj2/kxqB1xVB+EV7olGYdLR+8PkTfA6zbu+BJTt0Q5a9AGABZcqGxF8cS6GBH7pRVM/B1 8qWHpDg== X-Received: from pgbcr9.prod.google.com ([2002:a05:6a02:4109:b0:c08:3dd8:1e39]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a20:d12f:b0:38b:d95e:69a9 with SMTP id adf61e73a8af0-393acf898b1mr720567637.16.1770333270970; Thu, 05 Feb 2026 15:14:30 -0800 (PST) Date: Thu, 5 Feb 2026 15:14:29 -0800 In-Reply-To: Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260129011517.3545883-1-seanjc@google.com> <20260129011517.3545883-6-seanjc@google.com> Message-ID: Subject: Re: [RFC PATCH v5 05/45] KVM: TDX: Drop kvm_x86_ops.link_external_spt(), use .set_external_spte() for all From: Sean Christopherson To: Yan Zhao Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Kiryl Shutsemau , Paolo Bonzini , linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev, kvm@vger.kernel.org, Kai Huang , Rick Edgecombe , Vishal Annapurve , Ackerley Tng , Sagi Shahar , Binbin Wu , Xiaoyao Li , Isaku Yamahata Content-Type: text/plain; charset="us-ascii" On Wed, Feb 04, 2026, Yan Zhao wrote: > On Tue, Feb 03, 2026 at 08:05:05PM +0000, Sean Christopherson wrote: > > On Tue, Feb 03, 2026, Yan Zhao wrote: > > > On Wed, Jan 28, 2026 at 05:14:37PM -0800, Sean Christopherson wrote: > > > > static int __must_check set_external_spte_present(struct kvm *kvm, tdp_ptep_t sptep, > > > > gfn_t gfn, u64 *old_spte, > > > > u64 new_spte, int level) > > > > { > > > > - bool was_present = is_shadow_present_pte(*old_spte); > > > > - bool is_present = is_shadow_present_pte(new_spte); > > > > - bool is_leaf = is_present && is_last_spte(new_spte, level); > > > > - int ret = 0; > > > > - > > > > - KVM_BUG_ON(was_present, kvm); > > > > + int ret; > > > > > > > > lockdep_assert_held(&kvm->mmu_lock); > > > > + > > > > + if (KVM_BUG_ON(is_shadow_present_pte(*old_spte), kvm)) > > > > + return -EIO; > > > Why not move this check of is_shadow_present_pte() to tdx_sept_set_private_spte() > > > as well? > > > > The series gets there eventually, but as of this commit, @old_spte isn't plumbed > > into tdx_sept_set_private_spte(). > > > > > Or also check !is_shadow_present_pte(new_spte) in TDP MMU? > > > > Not sure I understand this suggestion. > Sorry. The accurate expression should be > "what about moving !is_shadow_present_pte(new_spte) to TDP MMU as well?". It's already there, in __tdp_mmu_set_spte_atomic(): /* * KVM doesn't currently support zapping or splitting mirror * SPTEs while holding mmu_lock for read. */ if (KVM_BUG_ON(is_shadow_present_pte(iter->old_spte), kvm) || KVM_BUG_ON(!is_shadow_present_pte(new_spte), kvm)) return -EBUSY; > > > And as Rick also mentioned, better to remove external in external_spt, e.g. > > > something like pt_page. > > > > Yeah, maybe sept_spt? > Hmm, here sept_spt is of type struct page, while sp->spt and sp->external_spt > represents VA. Not sure if it will cause confusion. How about sept_pt?