KVM: VMX: Clean up PI pre/post-block WARNs

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Move the WARN sanity checks out of the PI descriptor update loop so as
not to spam the kernel log if the condition is violated and the update
takes multiple attempts due to another writer.  This also eliminates a
few extra uops from the retry path.

Technically not checking every attempt could mean KVM will now fail to
WARN in a scenario that would have failed before, but any such failure
would be inherently racy as some other agent (CPU or device) would have
to concurrent modify the PI descriptor.

Add a helper to handle the actual write and more importantly to document
why the write may need to be retried.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211208015236.1616697-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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Sean Christopherson 2021-12-08 01:52:13 +00:00 • committed by Paolo Bonzini

parent 83c98007d9

commit 45af1bb99b

1 changed files with 23 additions and 12 deletions

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arch/x86/kvm/vmx/posted_intr.c

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