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David Woodhouse 28f719670f KVM: x86/xen: inject vCPU upcall vector when local APIC is enabled

[ Upstream commit 8e62bf2bfa46367e14d0ffdcde5aada08759497c ]

Linux guests since commit b1c3497e604d ("x86/xen: Add support for
HVMOP_set_evtchn_upcall_vector") in v6.0 onwards will use the per-vCPU
upcall vector when it's advertised in the Xen CPUID leaves.

This upcall is injected through the guest's local APIC as an MSI, unlike
the older system vector which was merely injected by the hypervisor any
time the CPU was able to receive an interrupt and the upcall_pending
flags is set in its vcpu_info.

Effectively, that makes the per-CPU upcall edge triggered instead of
level triggered, which results in the upcall being lost if the MSI is
delivered when the local APIC is *disabled*.

Xen checks the vcpu_info->evtchn_upcall_pending flag when the local APIC
for a vCPU is software enabled (in fact, on any write to the SPIV
register which doesn't disable the APIC). Do the same in KVM since KVM
doesn't provide a way for userspace to intervene and trap accesses to
the SPIV register of a local APIC emulated by KVM.

Fixes: fde0451be8fb3 ("KVM: x86/xen: Support per-vCPU event channel upcall via local APIC")
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240227115648.3104-3-dwmw2@infradead.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

2024-04-03 15:28:24 +02:00

alpha

rtc: Add support for configuring the UIP timeout for RTC reads

2024-01-31 16:18:56 -08:00

arc

work around gcc bugs with 'asm goto' with outputs

2024-02-23 09:24:47 +01:00

arm

arm: dts: marvell: Fix maxium->maxim typo in brownstone dts

2024-04-03 15:28:16 +02:00

arm64

arm64: dts: qcom: sm8550-mtp: correct WCD9385 TX port mapping