[PATCH v1 2/4] xen/pci: Introduce new CONFIG_HAS_PCI_ATS flag for PCI ATS functionality.

[Rahul Singh <rahul.singh@xxxxxxx>]

PCI ATS functionality is not enabled and tested for ARM architecture
but it is enabled for x86 and referenced in common passthrough/pci.c
code.

Therefore introducing the new flag to enable the ATS functionality for
x86 only to avoid issues for ARM architecture.

No functional change.

Signed-off-by: Rahul Singh <rahul.singh@xxxxxxx>
---
 xen/arch/x86/Kconfig                     |  1 +
 xen/drivers/passthrough/ats.h            | 24 ++++++++++++++++++++++++
 xen/drivers/passthrough/vtd/x86/Makefile |  2 +-
 xen/drivers/passthrough/x86/Makefile     |  2 +-
 xen/drivers/pci/Kconfig                  |  3 +++
 5 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig
index 24868aa6ad..31906e9c97 100644
--- a/xen/arch/x86/Kconfig
+++ b/xen/arch/x86/Kconfig
@@ -20,6 +20,7 @@ config X86
        select HAS_NS16550
        select HAS_PASSTHROUGH
        select HAS_PCI
+       select HAS_PCI_ATS
        select HAS_PDX
        select HAS_SCHED_GRANULARITY
        select HAS_UBSAN
diff --git a/xen/drivers/passthrough/ats.h b/xen/drivers/passthrough/ats.h
index 22ae209b37..a0af07b287 100644
--- a/xen/drivers/passthrough/ats.h
+++ b/xen/drivers/passthrough/ats.h
@@ -17,6 +17,8 @@
 
 #include <xen/pci_regs.h>
 
+#ifdef CONFIG_HAS_PCI_ATS
+
 #define ATS_REG_CAP    4
 #define ATS_REG_CTL    6
 #define ATS_QUEUE_DEPTH_MASK     0x1f
@@ -48,5 +50,27 @@ static inline int pci_ats_device(int seg, int bus, int devfn)
     return pci_find_ext_capability(seg, bus, devfn, PCI_EXT_CAP_ID_ATS);
 }
 
+#else
+
+static inline int enable_ats_device(struct pci_dev *pdev,
+                                    struct list_head *ats_list)
+{
+    return -ENODEV;
+}
+
+static inline void disable_ats_device(struct pci_dev *pdev) { }
+
+static inline int pci_ats_enabled(int seg, int bus, int devfn)
+{
+    return -ENODEV;
+}
+
+static inline int pci_ats_device(int seg, int bus, int devfn)
+{
+    return -ENODEV;
+}
+
+#endif /* CONFIG_HAS_PCI_ATS */
+
 #endif /* _ATS_H_ */
 
diff --git a/xen/drivers/passthrough/vtd/x86/Makefile 
b/xen/drivers/passthrough/vtd/x86/Makefile
index 4ef00a4c5b..60f79fe263 100644
--- a/xen/drivers/passthrough/vtd/x86/Makefile
+++ b/xen/drivers/passthrough/vtd/x86/Makefile
@@ -1,3 +1,3 @@
-obj-y += ats.o
+obj-$(CONFIG_HAS_PCI_ATS) += ats.o
 obj-$(CONFIG_HVM) += hvm.o
 obj-y += vtd.o
diff --git a/xen/drivers/passthrough/x86/Makefile 
b/xen/drivers/passthrough/x86/Makefile
index a70cf9460d..05e6f51f25 100644
--- a/xen/drivers/passthrough/x86/Makefile
+++ b/xen/drivers/passthrough/x86/Makefile
@@ -1,2 +1,2 @@
-obj-y += ats.o
+obj-$(CONFIG_HAS_PCI_ATS) += ats.o
 obj-y += iommu.o
diff --git a/xen/drivers/pci/Kconfig b/xen/drivers/pci/Kconfig
index 7da03fa13b..1588d4a91e 100644
--- a/xen/drivers/pci/Kconfig
+++ b/xen/drivers/pci/Kconfig
@@ -1,3 +1,6 @@
 
 config HAS_PCI
        bool
+
+config HAS_PCI_ATS
+       bool
-- 
2.17.1