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Mon, 12 Dec 2022 19:30:35 -0800 (PST) Reply-To: Sean Christopherson Date: Tue, 13 Dec 2022 03:30:26 +0000 In-Reply-To: <20221213033030.83345-1-seanjc@google.com> Mime-Version: 1.0 References: <20221213033030.83345-1-seanjc@google.com> X-Mailer: git-send-email 2.39.0.rc1.256.g54fd8350bd-goog Message-ID: <20221213033030.83345-2-seanjc@google.com> Subject: [PATCH 1/5] KVM: x86/mmu: Don't attempt to map leaf if target TDP MMU SPTE is frozen From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Robert Hoo , Greg Thelen , David Matlack , Ben Gardon , Mingwei Zhang Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Hoist the is_removed_spte() check above the "level =3D=3D goal_level" check when walking SPTEs during a TDP MMU page fault to avoid attempting to map a leaf entry if said entry is frozen by a different task/vCPU. ------------[ cut here ]------------ WARNING: CPU: 3 PID: 939 at arch/x86/kvm/mmu/tdp_mmu.c:653 kvm_tdp_mmu_ma= p+0x269/0x4b0 Modules linked in: kvm_intel CPU: 3 PID: 939 Comm: nx_huge_pages_t Not tainted 6.1.0-rc4+ #67 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:kvm_tdp_mmu_map+0x269/0x4b0 RSP: 0018:ffffc9000068fba8 EFLAGS: 00010246 RAX: 00000000000005a0 RBX: ffffc9000068fcc0 RCX: 0000000000000005 RDX: ffff88810741f000 RSI: ffff888107f04600 RDI: ffffc900006a3000 RBP: 060000010b000bf3 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 000ffffffffff000 R12: 0000000000000005 R13: ffff888113670000 R14: ffff888107464958 R15: 0000000000000000 FS: 00007f01c942c740(0000) GS:ffff888277cc0000(0000) knlGS:0000000000000= 000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000117013006 CR4: 0000000000172ea0 Call Trace: kvm_tdp_page_fault+0x10c/0x130 kvm_mmu_page_fault+0x103/0x680 vmx_handle_exit+0x132/0x5a0 [kvm_intel] vcpu_enter_guest+0x60c/0x16f0 kvm_arch_vcpu_ioctl_run+0x1e2/0x9d0 kvm_vcpu_ioctl+0x271/0x660 __x64_sys_ioctl+0x80/0xb0 do_syscall_64+0x2b/0x50 entry_SYSCALL_64_after_hwframe+0x46/0xb0 ---[ end trace 0000000000000000 ]--- Fixes: 63d28a25e04c ("KVM: x86/mmu: simplify kvm_tdp_mmu_map flow when gues= t has to retry") Cc: Robert Hoo Signed-off-by: Sean Christopherson Reviewed-by: Robert Hoo --- arch/x86/kvm/mmu/tdp_mmu.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 764f7c87286f..b740f38fedcc 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -1162,9 +1162,6 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm= _page_fault *fault) if (fault->nx_huge_page_workaround_enabled) disallowed_hugepage_adjust(fault, iter.old_spte, iter.level); =20 - if (iter.level =3D=3D fault->goal_level) - break; - /* * If SPTE has been frozen by another thread, just give up and * retry, avoiding unnecessary page table allocation and free. @@ -1172,6 +1169,9 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm= _page_fault *fault) if (is_removed_spte(iter.old_spte)) goto retry; =20 + if (iter.level =3D=3D fault->goal_level) + break; + /* Step down into the lower level page table if it exists. */ if (is_shadow_present_pte(iter.old_spte) && !is_large_pte(iter.old_spte)) --=20 2.39.0.rc1.256.g54fd8350bd-goog