[Xen-devel] [PATCH 2/2] Introduce xen_swiotlb variable that is set when Xen is running.

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

Having the 'xen_swiotlb' variable enabled causes all of the
IOMMU's to be disabled (except the Xen-SWIOTLB). It is in
essence a copy of what swiotlb variable does. However the swiotlb variable
cannot be used because it would turn on the non-Xen SWIOTLB.
---
 arch/x86/include/asm/dma-mapping.h |    1 +
 arch/x86/include/asm/xen/swiotlb.h |    4 +++-
 arch/x86/kernel/amd_iommu_init.c   |    2 +-
 arch/x86/kernel/aperture_64.c      |    2 +-
 arch/x86/kernel/pci-calgary_64.c   |    2 +-
 arch/x86/kernel/pci-dma.c          |    4 ++--
 arch/x86/kernel/pci-gart_64.c      |    2 +-
 arch/x86/kernel/pci-swiotlb.c      |    4 ++--
 arch/x86/xen/pci-swiotlb.c         |    3 +++
 9 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/dma-mapping.h 
b/arch/x86/include/asm/dma-mapping.h
index 1c3f943..01ef814 100644
--- a/arch/x86/include/asm/dma-mapping.h
+++ b/arch/x86/include/asm/dma-mapping.h
@@ -12,6 +12,7 @@
 #include <linux/dma-attrs.h>
 #include <asm/io.h>
 #include <asm/swiotlb.h>
+#include <asm/xen/swiotlb.h>
 #include <asm-generic/dma-coherent.h>
 
 extern dma_addr_t bad_dma_address;
diff --git a/arch/x86/include/asm/xen/swiotlb.h 
b/arch/x86/include/asm/xen/swiotlb.h
index d094f89..fd7e48a 100644
--- a/arch/x86/include/asm/xen/swiotlb.h
+++ b/arch/x86/include/asm/xen/swiotlb.h
@@ -2,9 +2,11 @@
 #define _ASM_X86_XEN_SWIOTLB_H
 
 #ifdef CONFIG_PCI_XEN
+extern int xen_swiotlb;
 extern void xen_swiotlb_init(void);
 #else
-static void xen_swiotlb_init(void) { }
+#define xen_swiotlb 0
+static inline void xen_swiotlb_init(void) { }
 #endif
 
 #endif
diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index c1b17e9..78ec74b 100644
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -1304,7 +1304,7 @@ static int __init early_amd_iommu_detect(struct 
acpi_table_header *table)
 
 void __init amd_iommu_detect(void)
 {
-       if (swiotlb || no_iommu || (iommu_detected && !gart_iommu_aperture))
+       if (swiotlb || xen_swiotlb || no_iommu || (iommu_detected && 
!gart_iommu_aperture))
                return;
 
        if (acpi_table_parse("IVRS", early_amd_iommu_detect) == 0) {
diff --git a/arch/x86/kernel/aperture_64.c b/arch/x86/kernel/aperture_64.c
index 676debf..6a50006 100644
--- a/arch/x86/kernel/aperture_64.c
+++ b/arch/x86/kernel/aperture_64.c
@@ -369,7 +369,7 @@ void __init gart_iommu_hole_init(void)
        int fix, slot, valid_agp = 0;
        int i, node;
 
-       if (gart_iommu_aperture_disabled || !fix_aperture ||
+       if (gart_iommu_aperture_disabled || !fix_aperture || xen_swiotlb ||
            !early_pci_allowed())
                return;
 
diff --git a/arch/x86/kernel/pci-calgary_64.c b/arch/x86/kernel/pci-calgary_64.c
index 971a3be..f7b8e1c 100644
--- a/arch/x86/kernel/pci-calgary_64.c
+++ b/arch/x86/kernel/pci-calgary_64.c
@@ -1357,7 +1357,7 @@ void __init detect_calgary(void)
         * if the user specified iommu=off or iommu=soft or we found
         * another HW IOMMU already, bail out.
         */
-       if (swiotlb || no_iommu || iommu_detected)
+       if (swiotlb || xen_swiotlb || no_iommu || iommu_detected)
                return;
 
        if (!use_calgary)
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 6b76948..1101a9f 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -122,6 +122,8 @@ void __init pci_iommu_alloc(void)
         * The order of these functions is important for
         * fall-back/fail-over reasons
         */
+       xen_swiotlb_init();
+
        gart_iommu_hole_init();
 
        detect_calgary();
@@ -130,8 +132,6 @@ void __init pci_iommu_alloc(void)
 
        amd_iommu_detect();
 
-       xen_swiotlb_init();
-
        pci_swiotlb_init();
 }
 
diff --git a/arch/x86/kernel/pci-gart_64.c b/arch/x86/kernel/pci-gart_64.c
index d2e56b8..f2c9f19 100644
--- a/arch/x86/kernel/pci-gart_64.c
+++ b/arch/x86/kernel/pci-gart_64.c
@@ -730,7 +730,7 @@ void __init gart_iommu_init(void)
                (agp_copy_info(agp_bridge, &info) < 0);
 #endif
 
-       if (swiotlb)
+       if (swiotlb || xen_swiotlb)
                return;
 
        /* Did we detect a different HW IOMMU? */
diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
index e8a3501..54a0fa9 100644
--- a/arch/x86/kernel/pci-swiotlb.c
+++ b/arch/x86/kernel/pci-swiotlb.c
@@ -47,10 +47,10 @@ void __init pci_swiotlb_init(void)
        /* don't initialize swiotlb if iommu=off (no_iommu=1) */
 #ifdef CONFIG_X86_64
        if ((!iommu_detected && !no_iommu && max_pfn > MAX_DMA32_PFN) ||
-               iommu_pass_through)
+               iommu_pass_through || !xen_swiotlb)
               swiotlb = 1;
 #endif
-       if (swiotlb_force)
+       if (swiotlb_force || !xen_swiotlb)
                swiotlb = 1;
        if (swiotlb) {
                printk(KERN_INFO "PCI-DMA: Using software bounce buffering for 
IO (SWIOTLB)\n");
diff --git a/arch/x86/xen/pci-swiotlb.c b/arch/x86/xen/pci-swiotlb.c
index 5e2c856..de2dd39 100644
--- a/arch/x86/xen/pci-swiotlb.c
+++ b/arch/x86/xen/pci-swiotlb.c
@@ -978,6 +978,8 @@ static struct dma_map_ops xen_swiotlb_dma_ops = {
        .dma_supported = NULL,
 };
 
+int xen_swiotlb __read_mostly;
+
 void __init xen_swiotlb_init(void)
 {
        if (xen_initial_domain()) {
@@ -985,5 +987,6 @@ void __init xen_swiotlb_init(void)
                xen_swiotlb_init_with_default_size(64 * (1<<20));       /* 
default to 64MB */
                dma_ops = &xen_swiotlb_dma_ops;
                iommu_detected = 1;
+               xen_swiotlb = 1;
        }
 }
-- 
1.6.2.5


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