This is a note to let you know that I've just added the patch titled
KVM: x86: Mask LVTPC when handling a PMI
to the 5.15-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-mask-lvtpc-when-handling-a-pmi.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a16eb25b09c02a54c1c1b449d4b6cfa2cf3f013a Mon Sep 17 00:00:00 2001
From: Jim Mattson <jmattson@xxxxxxxxxx>
Date: Mon, 25 Sep 2023 17:34:47 +0000
Subject: KVM: x86: Mask LVTPC when handling a PMI
From: Jim Mattson <jmattson@xxxxxxxxxx>
commit a16eb25b09c02a54c1c1b449d4b6cfa2cf3f013a upstream.
Per the SDM, "When the local APIC handles a performance-monitoring
counters interrupt, it automatically sets the mask flag in the LVT
performance counter register." Add this behavior to KVM's local APIC
emulation.
Failure to mask the LVTPC entry results in spurious PMIs, e.g. when
running Linux as a guest, PMI handlers that do a "late_ack" spew a large
number of "dazed and confused" spurious NMI warnings.
Fixes: f5132b01386b ("KVM: Expose a version 2 architectural PMU to a guests")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
Tested-by: Mingwei Zhang <mizhang@xxxxxxxxxx>
Signed-off-by: Mingwei Zhang <mizhang@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230925173448.3518223-3-mizhang@xxxxxxxxxx
[sean: massage changelog, correct Fixes]
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/lapic.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2411,13 +2411,17 @@ int kvm_apic_local_deliver(struct kvm_la
{
u32 reg = kvm_lapic_get_reg(apic, lvt_type);
int vector, mode, trig_mode;
+ int r;
if (kvm_apic_hw_enabled(apic) && !(reg & APIC_LVT_MASKED)) {
vector = reg & APIC_VECTOR_MASK;
mode = reg & APIC_MODE_MASK;
trig_mode = reg & APIC_LVT_LEVEL_TRIGGER;
- return __apic_accept_irq(apic, mode, vector, 1, trig_mode,
- NULL);
+
+ r = __apic_accept_irq(apic, mode, vector, 1, trig_mode, NULL);
+ if (r && lvt_type == APIC_LVTPC)
+ kvm_lapic_set_reg(apic, APIC_LVTPC, reg | APIC_LVT_MASKED);
+ return r;
}
return 0;
}
Patches currently in stable-queue which might be from jmattson@xxxxxxxxxx are
queue-5.15/kvm-x86-mask-lvtpc-when-handling-a-pmi.patch
