From: Michael Kelley <mikelley@microsoft.com> To: sthemmin@microsoft.com, kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, rafael@kernel.org, lenb@kernel.org, lorenzo.pieralisi@arm.com, robh@kernel.org, kw@linux.com, bhelgaas@google.com, hch@lst.de, m.szyprowski@samsung.com, robin.murphy@arm.com, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-pci@vger.kernel.org, iommu@lists.linux-foundation.org Cc: mikelley@microsoft.com Subject: [PATCH v3 2/2] PCI: hv: Propagate coherence from VMbus device to PCI device Date: Thu, 24 Mar 2022 09:14:52 -0700 [thread overview] Message-ID: <1648138492-2191-3-git-send-email-mikelley@microsoft.com> (raw) In-Reply-To: <1648138492-2191-1-git-send-email-mikelley@microsoft.com> 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> --- drivers/pci/controller/pci-hyperv.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c index ae0bc2f..88b3b56 100644 --- a/drivers/pci/controller/pci-hyperv.c +++ b/drivers/pci/controller/pci-hyperv.c @@ -3404,6 +3404,15 @@ static int hv_pci_probe(struct hv_device *hdev, hbus->bridge->domain_nr = dom; #ifdef CONFIG_X86 hbus->sysdata.domain = dom; +#elif defined(CONFIG_ARM64) + /* + * Set the PCI bus parent to be the corresponding VMbus + * device. Then the VMbus device will be assigned as the + * ACPI companion in pcibios_root_bridge_prepare() and + * pci_dma_configure() will propagate device coherence + * information to devices created on the bus. + */ + hbus->sysdata.parent = hdev->device.parent; #endif hbus->hdev = hdev; -- 1.8.3.1
WARNING: multiple messages have this Message-ID (diff)
From: Michael Kelley via iommu <iommu@lists.linux-foundation.org> To: sthemmin@microsoft.com, kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, rafael@kernel.org, lenb@kernel.org, lorenzo.pieralisi@arm.com, robh@kernel.org, kw@linux.com, bhelgaas@google.com, hch@lst.de, m.szyprowski@samsung.com, robin.murphy@arm.com, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-pci@vger.kernel.org, iommu@lists.linux-foundation.org Cc: mikelley@microsoft.com Subject: [PATCH v3 2/2] PCI: hv: Propagate coherence from VMbus device to PCI device Date: Thu, 24 Mar 2022 09:14:52 -0700 [thread overview] Message-ID: <1648138492-2191-3-git-send-email-mikelley@microsoft.com> (raw) In-Reply-To: <1648138492-2191-1-git-send-email-mikelley@microsoft.com> 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> --- drivers/pci/controller/pci-hyperv.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c index ae0bc2f..88b3b56 100644 --- a/drivers/pci/controller/pci-hyperv.c +++ b/drivers/pci/controller/pci-hyperv.c @@ -3404,6 +3404,15 @@ static int hv_pci_probe(struct hv_device *hdev, hbus->bridge->domain_nr = dom; #ifdef CONFIG_X86 hbus->sysdata.domain = dom; +#elif defined(CONFIG_ARM64) + /* + * Set the PCI bus parent to be the corresponding VMbus + * device. Then the VMbus device will be assigned as the + * ACPI companion in pcibios_root_bridge_prepare() and + * pci_dma_configure() will propagate device coherence + * information to devices created on the bus. + */ + hbus->sysdata.parent = hdev->device.parent; #endif hbus->hdev = hdev; -- 1.8.3.1 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2022-03-24 16:15 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-03-24 16:14 [PATCH v3 0/2] Fix coherence for VMbus and PCI pass-thru devices in Hyper-V VM Michael Kelley 2022-03-24 16:14 ` Michael Kelley via iommu 2022-03-24 16:14 ` [PATCH v3 1/2] Drivers: hv: vmbus: Propagate VMbus coherence to each VMbus device Michael Kelley 2022-03-24 16:14 ` Michael Kelley via iommu 2022-03-24 16:14 ` Michael Kelley [this message] 2022-03-24 16:14 ` [PATCH v3 2/2] PCI: hv: Propagate coherence from VMbus device to PCI device Michael Kelley via iommu 2022-03-29 12:15 ` [PATCH v3 0/2] Fix coherence for VMbus and PCI pass-thru devices in Hyper-V VM Wei Liu 2022-03-29 12:15 ` Wei Liu
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