20210123000334.3123628-2-seanjc@xxxxxxxxxx>
Message-ID: <2023051551-trespass-cobweb-1314@gregkh>
MIME-Version: 1.0
Content-Type: text/plain; charset=ANSI_X3.4-1968
Content-Transfer-Encoding: 8bit
X-stable: commit
X-Patchwork-Hint: ignore
This is a note to let you know that I've just added the patch titled
KVM: x86: Remove obsolete disabling of page faults in kvm_arch_vcpu_put()
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-x86-remove-obsolete-disabling-of-page-faults-in-kvm_arch_vcpu_put.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From stable-owner@xxxxxxxxxxxxxxx Wed May 10 20:16:27 2023
From: Rishabh Bhatnagar <risbhat@xxxxxxxxxx>
Date: Wed, 10 May 2023 18:15:42 +0000
Subject: KVM: x86: Remove obsolete disabling of page faults in kvm_arch_vcpu_put()
To: <gregkh@xxxxxxxxxxxxxxxxxxx>, <stable@xxxxxxxxxxxxxxx>
Cc: <lee@xxxxxxxxxx>, <seanjc@xxxxxxxxxx>, <kvm@xxxxxxxxxxxxxxx>, <bp@xxxxxxxxx>, <mingo@xxxxxxxxxx>, <tglx@xxxxxxxxxxxxx>, <pbonzini@xxxxxxxxxx>, <vkuznets@xxxxxxxxxx>, <wanpengli@xxxxxxxxxxx>, <jmattson@xxxxxxxxxx>, <joro@xxxxxxxxxx>, Rishabh Bhatnagar <risbhat@xxxxxxxxxx>, Allen Pais <apais@xxxxxxxxxxxxxxxxxxx>
Message-ID: <20230510181547.22451-5-risbhat@xxxxxxxxxx>
From: Rishabh Bhatnagar <risbhat@xxxxxxxxxx>
From: Sean Christopherson <seanjc@xxxxxxxxxx>
commit 19979fba9bfaeab427a8e106d915f0627c952828 upstream.
Remove the disabling of page faults across kvm_steal_time_set_preempted()
as KVM now accesses the steal time struct (shared with the guest) via a
cached mapping (see commit b043138246a4, "x86/KVM: Make sure
KVM_VCPU_FLUSH_TLB flag is not missed".) The cache lookup is flagged as
atomic, thus it would be a bug if KVM tried to resolve a new pfn, i.e.
we want the splat that would be reached via might_fault().
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Message-Id: <20210123000334.3123628-2-seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Rishabh Bhatnagar <risbhat@xxxxxxxxxx>
Tested-by: Allen Pais <apais@xxxxxxxxxxxxxxxxxxx>
Acked-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/x86.c | 10 ----------
1 file changed, 10 deletions(-)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4143,22 +4143,12 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *
vcpu->arch.preempted_in_kernel = !kvm_x86_ops.get_cpl(vcpu);
/*
- * Disable page faults because we're in atomic context here.
- * kvm_write_guest_offset_cached() would call might_fault()
- * that relies on pagefault_disable() to tell if there's a
- * bug. NOTE: the write to guest memory may not go through if
- * during postcopy live migration or if there's heavy guest
- * paging.
- */
- pagefault_disable();
- /*
* kvm_memslots() will be called by
* kvm_write_guest_offset_cached() so take the srcu lock.
*/
idx = srcu_read_lock(&vcpu->kvm->srcu);
kvm_steal_time_set_preempted(vcpu);
srcu_read_unlock(&vcpu->kvm->srcu, idx);
- pagefault_enable();
kvm_x86_ops.vcpu_put(vcpu);
vcpu->arch.last_host_tsc = rdtsc();
/*
Patches currently in stable-queue which might be from stable-owner@xxxxxxxxxxxxxxx are
queue-5.10/kvm-fix-steal-time-asm-constraints.patch
queue-5.10/kvm-x86-ensure-pv-tlb-flush-tracepoint-reflects-kvm-behavior.patch
queue-5.10/blk-crypto-make-blk_crypto_evict_key-more-robust.patch
queue-5.10/kvm-x86-do-not-report-preemption-if-the-steal-time-cache-is-stale.patch
queue-5.10/kvm-x86-do-not-set-st-preempted-when-going-back-to-user-space.patch
queue-5.10/kvm-x86-move-guest_pv_has-out-of-user_access-section.patch
queue-5.10/kvm-x86-fix-recording-of-guest-steal-time-preempted-status.patch
queue-5.10/blk-mq-release-crypto-keyslot-before-reporting-i-o-complete.patch
queue-5.10/kvm-x86-revalidate-steal-time-cache-if-msr-value-changes.patch
queue-5.10/blk-crypto-make-blk_crypto_evict_key-return-void.patch
queue-5.10/kvm-x86-remove-obsolete-disabling-of-page-faults-in-kvm_arch_vcpu_put.patch
