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Commit 15b100df authored by Alex Williamson's avatar Alex Williamson Committed by Bjorn Helgaas
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PCI: Claim ACS support for AMD southbridge devices 



AMD confirmed that peer-to-peer between these devices is
not possible.  We can therefore claim that they support a
subset of ACS.

Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Acked-by: default avatarDonald Dutile <ddutile@redhat.com>
parent 83db7e0b

drivers/pci/quirks.c

+50 −0
Original line number Diff line number Diff line
@@ -3295,11 +3295,61 @@ struct pci_dev *pci_get_dma_source(struct pci_dev *dev) 
	return pci_dev_get(dev);

}



/*

 * AMD has indicated that the devices below do not support peer-to-peer

 * in any system where they are found in the southbridge with an AMD

 * IOMMU in the system.  Multifunction devices that do not support

 * peer-to-peer between functions can claim to support a subset of ACS.

 * Such devices effectively enable request redirect (RR) and completion

 * redirect (CR) since all transactions are redirected to the upstream

 * root complex.

 *

 * http://permalink.gmane.org/gmane.comp.emulators.kvm.devel/94086

 * http://permalink.gmane.org/gmane.comp.emulators.kvm.devel/94102

 * http://permalink.gmane.org/gmane.comp.emulators.kvm.devel/99402

 *

 * 1002:4385 SBx00 SMBus Controller

 * 1002:439c SB7x0/SB8x0/SB9x0 IDE Controller

 * 1002:4383 SBx00 Azalia (Intel HDA)

 * 1002:439d SB7x0/SB8x0/SB9x0 LPC host controller

 * 1002:4384 SBx00 PCI to PCI Bridge

 * 1002:4399 SB7x0/SB8x0/SB9x0 USB OHCI2 Controller

 */

static int pci_quirk_amd_sb_acs(struct pci_dev *dev, u16 acs_flags)

{

#ifdef CONFIG_ACPI

	struct acpi_table_header *header = NULL;

	acpi_status status;



	/* Targeting multifunction devices on the SB (appears on root bus) */

	if (!dev->multifunction || !pci_is_root_bus(dev->bus))

		return -ENODEV;



	/* The IVRS table describes the AMD IOMMU */

	status = acpi_get_table("IVRS", 0, &header);

	if (ACPI_FAILURE(status))

		return -ENODEV;



	/* Filter out flags not applicable to multifunction */

	acs_flags &= (PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_EC | PCI_ACS_DT);



	return acs_flags & ~(PCI_ACS_RR | PCI_ACS_CR) ? 0 : 1;

#else

	return -ENODEV;

#endif

}



static const struct pci_dev_acs_enabled {

	u16 vendor;

	u16 device;

	int (*acs_enabled)(struct pci_dev *dev, u16 acs_flags);

} pci_dev_acs_enabled[] = {

	{ PCI_VENDOR_ID_ATI, 0x4385, pci_quirk_amd_sb_acs },

	{ PCI_VENDOR_ID_ATI, 0x439c, pci_quirk_amd_sb_acs },

	{ PCI_VENDOR_ID_ATI, 0x4383, pci_quirk_amd_sb_acs },

	{ PCI_VENDOR_ID_ATI, 0x439d, pci_quirk_amd_sb_acs },

	{ PCI_VENDOR_ID_ATI, 0x4384, pci_quirk_amd_sb_acs },

	{ PCI_VENDOR_ID_ATI, 0x4399, pci_quirk_amd_sb_acs },

	{ 0 }

};