[PATCH 07/10] Xen/x86/PCI: Add support for the Xen PCI subsystem

Jeremy Fitzhardinge
2009-05-13T03:09:49Z

From: Alex Nixon <alex.nixon@citrix.com>

On boot, the system will search to see if a Xen iommu/pci subsystem is
available. If the kernel detects it's running in a domain rather than
on bare hardware, this subsystem will be used. Otherwise, it falls
back to using hardware as usual.

The frontend stub lives in arch/x86/pci-xen.c, alongside other
sub-arch PCI init code (e.g. olpc.c)

(All subsequent fixes, API changes and swiotlb operations folded in.)

[ Impact: add core of Xen PCI support ]
Signed-off-by: Alex Nixon <alex.nixon@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: "H. Peter Anvin" <hpa@zytor.com>
Reviewed-by: Matthew Wilcox <willy@linux.intel.com>
---
arch/x86/Kconfig | 4 +
arch/x86/include/asm/io.h | 2 +
arch/x86/include/asm/pci_x86.h | 1 +
arch/x86/include/asm/xen/iommu.h | 12 ++
arch/x86/kernel/pci-dma.c | 3 +
arch/x86/pci/Makefile | 1 +
arch/x86/pci/init.c | 6 +
arch/x86/pci/xen.c | 51 +++++++
drivers/pci/Makefile | 2 +
drivers/pci/xen-iommu.c | 271 ++++++++++++++++++++++++++++++++++++++
10 files changed, 353 insertions(+), 0 deletions(-)
create mode 100644 arch/x86/include/asm/xen/iommu.h
create mode 100644 arch/x86/pci/xen.c
create mode 100644 drivers/pci/xen-iommu.c

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index df9e885..15cc23a 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1829,6 +1829,10 @@ config PCI_OLPC
def_bool y
depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)

+config PCI_XEN
+ def_bool y
+ depends on XEN_PCI_PASSTHROUGH || XEN_DOM0_PCI
+
config PCI_DOMAINS
def_bool y
depends on PCI
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 7373932..57c7b26 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -7,6 +7,8 @@
#include <asm-generic/int-ll64.h>
#include <asm/page.h>

+extern int isapnp_disable;
+
#define build_mmio_read(name, size, type, reg, barrier) \
static inline type name(const volatile void __iomem *addr) \
{ type ret; asm volatile("mov" size " %1,%0":reg (ret) \
diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h
index 5401ca2..34f03a4 100644
--- a/arch/x86/include/asm/pci_x86.h
+++ b/arch/x86/include/asm/pci_x86.h
@@ -107,6 +107,7 @@ extern int pci_direct_probe(void);
extern void pci_direct_init(int type);
extern void pci_pcbios_init(void);
extern int pci_olpc_init(void);
+extern int pci_xen_init(void);
extern void __init dmi_check_pciprobe(void);
extern void __init dmi_check_skip_isa_align(void);

diff --git a/arch/x86/include/asm/xen/iommu.h b/arch/x86/include/asm/xen/iommu.h
new file mode 100644
index 0000000..75df312
--- /dev/null
+++ b/arch/x86/include/asm/xen/iommu.h
@@ -0,0 +1,12 @@
+#ifndef ASM_X86__XEN_IOMMU_H
+
+#ifdef CONFIG_PCI_XEN
+extern void xen_iommu_init(void);
+#else
+static inline void xen_iommu_init(void)
+{
+}
+#endif
+
+#endif
+
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 745579b..e486c40 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -10,6 +10,7 @@
#include <asm/gart.h>
#include <asm/calgary.h>
#include <asm/amd_iommu.h>
+#include <asm/xen/iommu.h>

static int forbid_dac __read_mostly;

@@ -275,6 +276,8 @@ static int __init pci_iommu_init(void)
dma_debug_add_bus(&pci_bus_type);
#endif

+ xen_iommu_init();
+
calgary_iommu_init();

intel_iommu_init();
diff --git a/arch/x86/pci/Makefile b/arch/x86/pci/Makefile
index d49202e..64182c5 100644
--- a/arch/x86/pci/Makefile
+++ b/arch/x86/pci/Makefile
@@ -4,6 +4,7 @@ obj-$(CONFIG_PCI_BIOS) += pcbios.o
obj-$(CONFIG_PCI_MMCONFIG) += mmconfig_$(BITS).o direct.o mmconfig-shared.o
obj-$(CONFIG_PCI_DIRECT) += direct.o
obj-$(CONFIG_PCI_OLPC) += olpc.o
+obj-$(CONFIG_PCI_XEN) += xen.o

obj-y += fixup.o
obj-$(CONFIG_ACPI) += acpi.o
diff --git a/arch/x86/pci/init.c b/arch/x86/pci/init.c
index 25a1f8e..4e2f90a 100644
--- a/arch/x86/pci/init.c
+++ b/arch/x86/pci/init.c
@@ -15,10 +15,16 @@ static __init int pci_arch_init(void)
if (!(pci_probe & PCI_PROBE_NOEARLY))
pci_mmcfg_early_init();

+#ifdef CONFIG_PCI_XEN
+ if (!pci_xen_init())
+ return 0;
+#endif
+
#ifdef CONFIG_PCI_OLPC
if (!pci_olpc_init())
return 0; /* skip additional checks if it's an XO */
#endif
+
#ifdef CONFIG_PCI_BIOS
pci_pcbios_init();
#endif
diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
new file mode 100644
index 0000000..1b922aa
--- /dev/null
+++ b/arch/x86/pci/xen.c
@@ -0,0 +1,51 @@
+/*
+ * Xen PCI Frontend Stub - puts some "dummy" functions in to the Linux
+ * x86 PCI core to support the Xen PCI Frontend
+ *
+ * Author: Ryan Wilson <hap9@epoch.ncsc.mil>
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/pci.h>
+#include <linux/acpi.h>
+
+#include <asm/io.h>
+#include <asm/pci_x86.h>
+
+#include <asm/xen/hypervisor.h>
+
+static int xen_pcifront_enable_irq(struct pci_dev *dev)
+{
+ return 0;
+}
+
+int __init pci_xen_init(void)
+{
+ if (!xen_pv_domain() || xen_initial_domain())
+ return -ENODEV;
+
+ printk(KERN_INFO "PCI: setting up Xen PCI frontend stub\n");
+
+ pcibios_set_cache_line_size();
+
+ pcibios_enable_irq = xen_pcifront_enable_irq;
+ pcibios_disable_irq = NULL;
+
+#ifdef CONFIG_ACPI
+ /* Keep ACPI out of the picture */
+ acpi_noirq = 1;
+#endif
+
+#ifdef CONFIG_ISAPNP
+ /* Stop isapnp from probing */
+ isapnp_disable = 1;
+#endif
+
+ /* Ensure a device still gets scanned even if it's fn number
+ * is non-zero.
+ */
+ pci_scan_all_fns = 1;
+
+ return 0;
+}
+
diff --git a/drivers/pci/Makefile b/drivers/pci/Makefile
index ba6af16..8db0cb5 100644
--- a/drivers/pci/Makefile
+++ b/drivers/pci/Makefile
@@ -27,6 +27,8 @@ obj-$(CONFIG_HT_IRQ) += htirq.o
# Build Intel IOMMU support
obj-$(CONFIG_DMAR) += dmar.o iova.o intel-iommu.o

+# Build Xen IOMMU support
+obj-$(CONFIG_PCI_XEN) += xen-iommu.o
obj-$(CONFIG_INTR_REMAP) += dmar.o intr_remapping.o

obj-$(CONFIG_PCI_IOV) += iov.o
diff --git a/drivers/pci/xen-iommu.c b/drivers/pci/xen-iommu.c
new file mode 100644
index 0000000..ac6bcdb
--- /dev/null
+++ b/drivers/pci/xen-iommu.c
@@ -0,0 +1,271 @@
+#include <linux/types.h>
+#include <linux/mm.h>
+#include <linux/string.h>
+#include <linux/pci.h>
+#include <linux/module.h>
+#include <linux/version.h>
+#include <linux/scatterlist.h>
+#include <linux/io.h>
+#include <linux/bug.h>
+
+#include <xen/interface/xen.h>
+#include <xen/grant_table.h>
+#include <xen/page.h>
+#include <xen/xen-ops.h>
+
+#include <asm/iommu.h>
+#include <asm/swiotlb.h>
+#include <asm/tlbflush.h>
+
+#define IOMMU_BUG_ON(test) \
+do { \
+ if (unlikely(test)) { \
+ printk(KERN_ALERT "Fatal DMA error! " \
+ "Please use 'swiotlb=force'\n"); \
+ BUG(); \
+ } \
+} while (0)
+
+/* Print address range with message */
+#define PAR(msg, addr, size) \
+do { \
+ printk(msg "[%#llx - %#llx]\n", \
+ (unsigned long long)addr, \
+ (unsigned long long)addr + size); \
+} while (0)
+
+static inline int address_needs_mapping(struct device *hwdev,
+ dma_addr_t addr)
+{
+ dma_addr_t mask = DMA_BIT_MASK(32);
+ int ret;
+
+ /* If the device has a mask, use it, otherwise default to 32 bits */
+ if (hwdev)
+ mask = *hwdev->dma_mask;
+
+ ret = (addr & ~mask) != 0;
+
+ if (ret) {
+ printk(KERN_ERR "dma address needs mapping\n");
+ printk(KERN_ERR "mask: %#llx\n address: [%#llx]\n", mask, addr);
+ }
+ return ret;
+}
+
+static int check_pages_physically_contiguous(unsigned long pfn,
+ unsigned int offset,
+ size_t length)
+{
+ unsigned long next_mfn;
+ int i;
+ int nr_pages;
+
+ next_mfn = pfn_to_mfn(pfn);
+ nr_pages = (offset + length + PAGE_SIZE-1) >> PAGE_SHIFT;
+
+ for (i = 1; i < nr_pages; i++) {
+ if (pfn_to_mfn(++pfn) != ++next_mfn)
+ return 0;
+ }
+ return 1;
+}
+
+static int range_straddles_page_boundary(phys_addr_t p, size_t size)
+{
+ unsigned long pfn = PFN_DOWN(p);
+ unsigned int offset = p & ~PAGE_MASK;
+
+ if (offset + size <= PAGE_SIZE)
+ return 0;
+ if (check_pages_physically_contiguous(pfn, offset, size))
+ return 0;
+ return 1;
+}
+
+static inline void xen_dma_unmap_page(struct page *page)
+{
+ /* Xen TODO: 2.6.18 xen calls __gnttab_dma_unmap_page here
+ * to deal with foreign pages. We'll need similar logic here at
+ * some point.
+ */
+}
+
+/* Gets dma address of a page */
+static inline dma_addr_t xen_dma_map_page(struct page *page)
+{
+ /* Xen TODO: 2.6.18 xen calls __gnttab_dma_map_page here to deal
+ * with foreign pages. We'll need similar logic here at some
+ * point.
+ */
+ return ((dma_addr_t)pfn_to_mfn(page_to_pfn(page))) << PAGE_SHIFT;
+}
+
+static int xen_map_sg(struct device *hwdev, struct scatterlist *sg,
+ int nents,
+ enum dma_data_direction direction,
+ struct dma_attrs *attrs)
+{
+ struct scatterlist *s;
+ struct page *page;
+ int i, rc;
+
+ BUG_ON(direction == DMA_NONE);
+ WARN_ON(nents == 0 || sg[0].length == 0);
+
+ for_each_sg(sg, s, nents, i) {
+ BUG_ON(!sg_page(s));
+ page = sg_page(s);
+ s->dma_address = xen_dma_map_page(page) + s->offset;
+ s->dma_length = s->length;
+ IOMMU_BUG_ON(range_straddles_page_boundary(
+ page_to_phys(page), s->length));
+ }
+
+ rc = nents;
+
+ flush_write_buffers();
+ return rc;
+}
+
+static void xen_unmap_sg(struct device *hwdev, struct scatterlist *sg,
+ int nents,
+ enum dma_data_direction direction,
+ struct dma_attrs *attrs)
+{
+ struct scatterlist *s;
+ struct page *page;
+ int i;
+
+ for_each_sg(sg, s, nents, i) {
+ page = pfn_to_page(mfn_to_pfn(PFN_DOWN(s->dma_address)));
+ xen_dma_unmap_page(page);
+ }
+}
+
+static void *xen_alloc_coherent(struct device *dev, size_t size,
+ dma_addr_t *dma_handle, gfp_t gfp)
+{
+ void *ret;
+ unsigned int order = get_order(size);
+ unsigned long vstart;
+ u64 mask;
+
+ /* ignore region specifiers */
+ gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);
+
+ if (dma_alloc_from_coherent(dev, size, dma_handle, &ret))
+ return ret;
+
+ if (dev == NULL || (dev->coherent_dma_mask < DMA_BIT_MASK(32)))
+ gfp |= GFP_DMA;
+
+ vstart = __get_free_pages(gfp, order);
+ ret = (void *)vstart;
+
+ if (dev != NULL && dev->coherent_dma_mask)
+ mask = dev->coherent_dma_mask;
+ else
+ mask = DMA_BIT_MASK(32);
+
+ if (ret != NULL) {
+ if (xen_create_contiguous_region(vstart, order,
+ fls64(mask)) != 0) {
+ free_pages(vstart, order);
+ return NULL;
+ }
+ memset(ret, 0, size);
+ *dma_handle = virt_to_machine(ret).maddr;
+ }
+ return ret;
+}
+
+static void xen_free_coherent(struct device *dev, size_t size,
+ void *vaddr, dma_addr_t dma_addr)
+{
+ int order = get_order(size);
+
+ if (dma_release_from_coherent(dev, order, vaddr))
+ return;
+
+ xen_destroy_contiguous_region((unsigned long)vaddr, order);
+ free_pages((unsigned long)vaddr, order);
+}
+
+static dma_addr_t xen_map_page(struct device *dev, struct page *page,
+ unsigned long offset, size_t size,
+ enum dma_data_direction direction,
+ struct dma_attrs *attrs)
+{
+ dma_addr_t dma;
+
+ BUG_ON(direction == DMA_NONE);
+
+ WARN_ON(size == 0);
+
+ dma = xen_dma_map_page(page) + offset;
+
+ IOMMU_BUG_ON(address_needs_mapping(dev, dma));
+ flush_write_buffers();
+ return dma;
+}
+
+static void xen_unmap_page(struct device *dev, dma_addr_t dma_addr,
+ size_t size,
+ enum dma_data_direction direction,
+ struct dma_attrs *attrs)
+{
+ BUG_ON(direction == DMA_NONE);
+ xen_dma_unmap_page(pfn_to_page(mfn_to_pfn(PFN_DOWN(dma_addr))));
+}
+
+static struct dma_map_ops xen_dma_ops = {
+ .dma_supported = NULL,
+
+ .alloc_coherent = xen_alloc_coherent,
+ .free_coherent = xen_free_coherent,
+
+ .map_page = xen_map_page,
+ .unmap_page = xen_unmap_page,
+
+ .map_sg = xen_map_sg,
+ .unmap_sg = xen_unmap_sg,
+
+ .mapping_error = NULL,
+
+ .is_phys = 0,
+};
+
+static struct dma_map_ops xen_swiotlb_dma_ops = {
+ .dma_supported = swiotlb_dma_supported,
+
+ .alloc_coherent = xen_alloc_coherent,
+ .free_coherent = xen_free_coherent,
+
+ .map_page = swiotlb_map_page,
+ .unmap_page = swiotlb_unmap_page,
+
+ .map_sg = swiotlb_map_sg_attrs,
+ .unmap_sg = swiotlb_unmap_sg_attrs,
+
+ .mapping_error = swiotlb_dma_mapping_error,
+
+ .is_phys = 0,
+};
+
+void __init xen_iommu_init(void)
+{
+ if (!xen_pv_domain())
+ return;
+
+ printk(KERN_INFO "Xen: Initializing Xen DMA ops\n");
+
+ force_iommu = 0;
+ dma_ops = &xen_dma_ops;
+
+ if (swiotlb) {
+ printk(KERN_INFO "Xen: Enabling DMA fallback to swiotlb\n");
+ dma_ops = &xen_swiotlb_dma_ops;
+ }
+}
+
--
1.6.0.6