From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Robert Hoo <robert.hu@linux.intel.com>,
Greg Thelen <gthelen@google.com>,
David Matlack <dmatlack@google.com>,
Ben Gardon <bgardon@google.com>,
Mingwei Zhang <mizhang@google.com>
Subject: [PATCH 1/5] KVM: x86/mmu: Don't attempt to map leaf if target TDP MMU SPTE is frozen
Date: Tue, 13 Dec 2022 03:30:26 +0000 [thread overview]
Message-ID: <20221213033030.83345-2-seanjc@google.com> (raw)
In-Reply-To: <20221213033030.83345-1-seanjc@google.com>
Hoist the is_removed_spte() check above the "level == 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_map+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:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000117013006 CR4: 0000000000172ea0
Call Trace:
<TASK>
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
</TASK>
---[ end trace 0000000000000000 ]---
Fixes: 63d28a25e04c ("KVM: x86/mmu: simplify kvm_tdp_mmu_map flow when guest has to retry")
Cc: Robert Hoo <robert.hu@linux.intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
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);
- if (iter.level == 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;
+ if (iter.level == 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))
--
2.39.0.rc1.256.g54fd8350bd-goog
next prev parent reply other threads:[~2022-12-13 3:30 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-13 3:30 [PATCH 0/5] KVM: x86/mmu: TDP MMU fixes for 6.2 Sean Christopherson
2022-12-13 3:30 ` Sean Christopherson [this message]
2022-12-14 11:57 ` [PATCH 1/5] KVM: x86/mmu: Don't attempt to map leaf if target TDP MMU SPTE is frozen Robert Hoo
2022-12-13 3:30 ` [PATCH 2/5] KVM: x86/mmu: Map TDP MMU leaf SPTE iff target level is reached Sean Christopherson
2022-12-13 3:30 ` [PATCH 3/5] KVM: x86/mmu: Re-check under lock that TDP MMU SP hugepage is disallowed Sean Christopherson
2022-12-14 11:58 ` Robert Hoo
2022-12-15 0:11 ` Sean Christopherson
2022-12-15 6:26 ` Robert Hoo
2022-12-13 3:30 ` [PATCH 4/5] KVM: x86/mmu: Don't install TDP MMU SPTE if SP has unexpected level Sean Christopherson
2022-12-13 17:59 ` David Matlack
2022-12-13 18:15 ` Sean Christopherson
2022-12-20 18:24 ` David Matlack
2022-12-13 3:30 ` [PATCH 5/5] KVM: x86/mmu: Move kvm_tdp_mmu_map()'s prolog and epilog to its caller Sean Christopherson
2022-12-20 17:53 ` David Matlack
2022-12-21 18:32 ` Sean Christopherson
2022-12-29 19:51 ` David Matlack
2022-12-29 21:06 ` Paolo Bonzini
2023-01-03 22:21 ` David Matlack
2022-12-14 12:01 ` [PATCH 0/5] KVM: x86/mmu: TDP MMU fixes for 6.2 Robert Hoo
2022-12-14 15:48 ` Sean Christopherson
2022-12-23 17:32 ` Paolo Bonzini
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