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authorMichael Kelley <mikelley@microsoft.com>2022-03-24 09:14:52 -0700
committerWei Liu <wei.liu@kernel.org>2022-03-29 12:12:50 +0000
commit8d21732475c637c7efcdb91dc927a4c594e97898 (patch)
tree1ac06132324efd4ec5d0f39c0de24ec9687d3995 /drivers/hv
parent37200078ed6aa2ac3c88a01a64996133dccfdd34 (diff)
PCI: hv: Propagate coherence from VMbus device to PCI device
PCI pass-thru devices in a Hyper-V VM are represented as a VMBus device and as a PCI device. The coherence of the VMbus device is set based on the VMbus node in ACPI, but the PCI device has no ACPI node and defaults to not hardware coherent. This results in extra software coherence management overhead on ARM64 when devices are hardware coherent. Fix this by setting up the PCI host bus so that normal PCI mechanisms will propagate the coherence of the VMbus device to the PCI device. There's no effect on x86/x64 where devices are always hardware coherent. Signed-off-by: Michael Kelley <mikelley@microsoft.com> Acked-by: Boqun Feng <boqun.feng@gmail.com> Acked-by: Robin Murphy <robin.murphy@arm.com> Link: https://lore.kernel.org/r/1648138492-2191-3-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
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