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author | jc_gargma <jc_gargma@iserlohn-fortress.net> | 2020-05-06 15:49:54 -0700 |
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committer | jc_gargma <jc_gargma@iserlohn-fortress.net> | 2020-05-06 15:49:54 -0700 |
commit | 8576b9d220ed4f6b60b8ad50e83ca8914df3fa65 (patch) | |
tree | 282a1d00c515c46563773594f75daa3e9824e5c8 /0002-kvm-ioapic-Restrict-lazy-EOI-update-to-edge-triggered-interrupts.patch | |
parent | Updated to 5.6.10 (diff) | |
download | linux-ck-8576b9d220ed4f6b60b8ad50e83ca8914df3fa65.tar.xz |
Updated to 5.6.11
Diffstat (limited to '0002-kvm-ioapic-Restrict-lazy-EOI-update-to-edge-triggered-interrupts.patch')
-rw-r--r-- | 0002-kvm-ioapic-Restrict-lazy-EOI-update-to-edge-triggered-interrupts.patch | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/0002-kvm-ioapic-Restrict-lazy-EOI-update-to-edge-triggered-interrupts.patch b/0002-kvm-ioapic-Restrict-lazy-EOI-update-to-edge-triggered-interrupts.patch new file mode 100644 index 0000000..b887a12 --- /dev/null +++ b/0002-kvm-ioapic-Restrict-lazy-EOI-update-to-edge-triggered-interrupts.patch @@ -0,0 +1,78 @@ +From da707adaee9ff035c943178160be54a90de00cb3 Mon Sep 17 00:00:00 2001 +From: Paolo Bonzini <pbonzini@redhat.com> +Date: Mon, 4 May 2020 12:19:45 -0400 +Subject: kvm: ioapic: Restrict lazy EOI update to edge-triggered interrupts + +Commit f458d039db7e ("kvm: ioapic: Lazy update IOAPIC EOI") introduces +the following infinite loop: + +BUG: stack guard page was hit at 000000008f595917 \ +(stack is 00000000bdefe5a4..00000000ae2b06f5) +kernel stack overflow (double-fault): 0000 [#1] SMP NOPTI +RIP: 0010:kvm_set_irq+0x51/0x160 [kvm] +Call Trace: + irqfd_resampler_ack+0x32/0x90 [kvm] + kvm_notify_acked_irq+0x62/0xd0 [kvm] + kvm_ioapic_update_eoi_one.isra.0+0x30/0x120 [kvm] + ioapic_set_irq+0x20e/0x240 [kvm] + kvm_ioapic_set_irq+0x5c/0x80 [kvm] + kvm_set_irq+0xbb/0x160 [kvm] + ? kvm_hv_set_sint+0x20/0x20 [kvm] + irqfd_resampler_ack+0x32/0x90 [kvm] + kvm_notify_acked_irq+0x62/0xd0 [kvm] + kvm_ioapic_update_eoi_one.isra.0+0x30/0x120 [kvm] + ioapic_set_irq+0x20e/0x240 [kvm] + kvm_ioapic_set_irq+0x5c/0x80 [kvm] + kvm_set_irq+0xbb/0x160 [kvm] + ? kvm_hv_set_sint+0x20/0x20 [kvm] +.... + +The re-entrancy happens because the irq state is the OR of +the interrupt state and the resamplefd state. That is, we don't +want to show the state as 0 until we've had a chance to set the +resamplefd. But if the interrupt has _not_ gone low then +ioapic_set_irq is invoked again, causing an infinite loop. + +This can only happen for a level-triggered interrupt, otherwise +irqfd_inject would immediately set the KVM_USERSPACE_IRQ_SOURCE_ID high +and then low. Fortunately, in the case of level-triggered interrupts the VMEXIT already happens because +TMR is set. Thus, fix the bug by restricting the lazy invocation +of the ack notifier to edge-triggered interrupts, the only ones that +need it. + +Tested-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> +Reported-by: borisvk@bstnet.org +Suggested-by: Paolo Bonzini <pbonzini@redhat.com> +Link: https://www.spinics.net/lists/kvm/msg213512.html +Fixes: f458d039db7e ("kvm: ioapic: Lazy update IOAPIC EOI") +Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=207489 +Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> +--- + arch/x86/kvm/ioapic.c | 10 +++++----- + 1 file changed, 5 insertions(+), 5 deletions(-) + +diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c +index 750ff0b29404..d057376bd3d3 100644 +--- a/arch/x86/kvm/ioapic.c ++++ b/arch/x86/kvm/ioapic.c +@@ -225,12 +225,12 @@ static int ioapic_set_irq(struct kvm_ioapic *ioapic, unsigned int irq, + } + + /* +- * AMD SVM AVIC accelerate EOI write and do not trap, +- * in-kernel IOAPIC will not be able to receive the EOI. +- * In this case, we do lazy update of the pending EOI when +- * trying to set IOAPIC irq. ++ * AMD SVM AVIC accelerate EOI write iff the interrupt is edge ++ * triggered, in which case the in-kernel IOAPIC will not be able ++ * to receive the EOI. In this case, we do a lazy update of the ++ * pending EOI when trying to set IOAPIC irq. + */ +- if (kvm_apicv_activated(ioapic->kvm)) ++ if (edge && kvm_apicv_activated(ioapic->kvm)) + ioapic_lazy_update_eoi(ioapic, irq); + + /* +-- +cgit v1.2.3-1-gf6bb5 + |