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AJvYcCUilBNKt36/zPsYVzX8yUNF3hUnHakfNArSNT5+QZFAdV7/8u0a6NW7EvKUZWIoRAVzQVur4MzFO5BgMY8=@vger.kernel.org X-Gm-Message-State: AOJu0Ywzl/R9IGL/DV+kfUpoavj3W2yM3mg19DS3BHJ330lAyEy4xcpD C7GkGCMpFaTGIu2l99jDfuRaHCpBKzkbJeSPqLri4SYXijeStuGiJqsBm2an3mOT6QGVPXKdumD 3wwA1Pg== X-Google-Smtp-Source: AGHT+IEiAetaI+89aihaa4gzEoo2ZAl9jtG5VdIpcIRh8HZt4Cs8pqUG+YboDBBirpw/HkYzrzcdv9vN4Q4= X-Received: from pgbct9.prod.google.com ([2002:a05:6a02:2109:b0:b20:93aa:6141]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a21:1512:b0:21e:eb3a:dc04 with SMTP id adf61e73a8af0-21fbd495d28mr946071637.3.1749845800007; Fri, 13 Jun 2025 13:16:40 -0700 (PDT) Date: Fri, 13 Jun 2025 13:16:38 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250612044943.151258-1-pbonzini@redhat.com> Message-ID: Subject: Re: [PATCH] KVM: x86/mmu: Reject direct bits in gpa passed to KVM_PRE_FAULT_MEMORY From: Sean Christopherson To: Yan Zhao Cc: Paolo Bonzini , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, xiaoyao.li@intel.com Content-Type: text/plain; charset="us-ascii" On Fri, Jun 13, 2025, Yan Zhao wrote: > On Thu, Jun 12, 2025 at 12:49:43AM -0400, Paolo Bonzini wrote: > > Only let userspace pass the same addresses that were used in KVM_SET_USER_MEMORY_REGION > > (or KVM_SET_USER_MEMORY_REGION2); gpas in the the upper half of the address space > > are an implementation detail of TDX and KVM. > > > > Extracted from a patch by Sean Christopherson . > > > > Signed-off-by: Paolo Bonzini > > --- > > arch/x86/kvm/mmu/mmu.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > > index a4040578b537..4e06e2e89a8f 100644 > > --- a/arch/x86/kvm/mmu/mmu.c > > +++ b/arch/x86/kvm/mmu/mmu.c > > @@ -4903,6 +4903,9 @@ long kvm_arch_vcpu_pre_fault_memory(struct kvm_vcpu *vcpu, > > if (!vcpu->kvm->arch.pre_fault_allowed) > > return -EOPNOTSUPP; > > > > + if (kvm_is_gfn_alias(vcpu->kvm, gpa_to_gfn(range->gpa))) > > + return -EINVAL; > > + > Do we need the same check in kvm_vm_ioctl_set_mem_attributes()? Yeah, we probably should disallow aliases there. It should be benign? Because memslots disallow aliases, and so the aliased gfn entries in the xarray will never actually be consumed.