PCI: add pci_request_acs

Commit ae21ee6 "PCI: acs p2p upsteram forwarding enabling" doesn't actually enable ACS. Add a function to pci core to allow an IOMMU to request that ACS be enabled. The existing mechanism of using iommu_found() in the pci core to know when ACS should be enabled doesn't actually work due to initialization order; iommu has only been detected not initialized. Have Intel and AMD IOMMUs request ACS, and Xen does as well during early init of dom0. Cc: Allen Kay <[email protected]> Cc: David Woodhouse <[email protected]> Cc: Jeremy Fitzhardinge <[email protected]> Cc: Joerg Roedel <[email protected]> Signed-off-by: Chris Wright <[email protected]> Signed-off-by: Jesse Barnes <[email protected]>
marineam · Dec 5, 2009 · 5d990b6 · 5d990b6
1 parent b26a34a
commit 5d990b6
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Showing 6 changed files with 27 additions and 5 deletions.
diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
@@ -1330,6 +1330,8 @@ void __init amd_iommu_detect(void)
 		gart_iommu_aperture_disabled = 1;
 		gart_iommu_aperture = 0;
 #endif
+		/* Make sure ACS will be enabled */
+		pci_request_acs();
 	}
 }
 

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
@@ -27,6 +27,7 @@
 #include <linux/page-flags.h>
 #include <linux/highmem.h>
 #include <linux/console.h>
+#include <linux/pci.h>
 
 #include <xen/xen.h>
 #include <xen/interface/xen.h>
@@ -1170,7 +1171,11 @@ asmlinkage void __init xen_start_kernel(void)
 		add_preferred_console("xenboot", 0, NULL);
 		add_preferred_console("tty", 0, NULL);
 		add_preferred_console("hvc", 0, NULL);
+	} else {
+		/* Make sure ACS will be enabled */
+		pci_request_acs();
 	}
+
 
 	xen_raw_console_write("about to get started...\n");
 

diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
@@ -614,8 +614,11 @@ void __init detect_intel_iommu(void)
 #endif
 #ifdef CONFIG_DMAR
 		if (ret && !no_iommu && !iommu_detected && !swiotlb &&
-		    !dmar_disabled)
+		    !dmar_disabled) {
 			iommu_detected = 1;
+			/* Make sure ACS will be enabled */
+			pci_request_acs();
+		}
 #endif
 	}
 	early_acpi_os_unmap_memory(dmar_tbl, dmar_tbl_size);

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
@@ -1550,6 +1550,16 @@ void pci_enable_ari(struct pci_dev *dev)
 	bridge->ari_enabled = 1;
 }
 
+static int pci_acs_enable;
+
+/**
+ * pci_request_acs - ask for ACS to be enabled if supported
+ */
+void pci_request_acs(void)
+{
+	pci_acs_enable = 1;
+}
+
 /**
  * pci_enable_acs - enable ACS if hardware support it
  * @dev: the PCI device
@@ -1560,6 +1570,9 @@ void pci_enable_acs(struct pci_dev *dev)
 	u16 cap;
 	u16 ctrl;
 
+	if (!pci_acs_enable)
+		return;
+
 	if (!pci_is_pcie(dev))
 		return;
 

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
@@ -10,9 +10,7 @@
 #include <linux/module.h>
 #include <linux/cpumask.h>
 #include <linux/pci-aspm.h>
-#include <linux/iommu.h>
 #include <acpi/acpi_hest.h>
-#include <xen/xen.h>
 #include "pci.h"
 
 #define CARDBUS_LATENCY_TIMER	176	/* secondary latency timer */
@@ -1029,8 +1027,7 @@ static void pci_init_capabilities(struct pci_dev *dev)
 	pci_iov_init(dev);
 
 	/* Enable ACS P2P upstream forwarding */
-	if (iommu_found() || xen_initial_domain())
-		pci_enable_acs(dev);
+	pci_enable_acs(dev);
 }
 
 void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)

diff --git a/include/linux/pci.h b/include/linux/pci.h
@@ -1328,5 +1328,7 @@ static inline bool pci_is_pcie(struct pci_dev *dev)
 	return !!pci_pcie_cap(dev);
 }
 
+void pci_request_acs(void);
+
 #endif /* __KERNEL__ */
 #endif /* LINUX_PCI_H */