[PATCH v2 1/1] xen/pci: Install vpci handlers on x86 and fix exit path

[Bertrand Marquis <bertrand.marquis@xxxxxxx>]

Xen might not be able to discover at boot time all devices or some devices
might appear after specific actions from dom0.
In this case dom0 can use the PHYSDEVOP_pci_device_add to signal some
PCI devices to Xen.
As those devices where not known from Xen before, the vpci handlers must
be properly installed during pci_device_add for x86 PVH Dom0, in the
same way as what is done currently on arm (where Xen does not detect PCI
devices but relies on Dom0 to declare them all the time).

So this patch is removing the ifdef protecting the call to
vpci_add_handlers and the comment which was arm specific.

vpci_add_handlers is called on during pci_device_add which can be called
at runtime through hypercall physdev_op.
Remove __hwdom_init as the call is not limited anymore to hardware
domain init and fix linker script to only keep vpci_array in rodata
section.

Add missing vpci handlers cleanup during pci_device_remove and in case
of error with iommu during pci_device_add.

Add empty static inline for vpci_remove_device when CONFIG_VPCI is not
defined.

Fixes: d59168dc05 ("xen/arm: Enable the existing x86 virtual PCI support
for ARM")
Suggested-by: Jan Beulich <jbeulich@xxxxxxxx>
Signed-off-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
---
Changes in v2
- add comment suggested by Jan on top of vpci_add_handlers call
- merge the 3 patches of the serie in one patch and renamed it
- fix x86 and arm linker script to only keep vpci_array in rodata and
only when CONFIG_VPCI is set.
---
 xen/arch/arm/xen.lds.S        | 9 +--------
 xen/arch/x86/xen.lds.S        | 9 +--------
 xen/drivers/passthrough/pci.c | 8 ++++----
 xen/drivers/vpci/vpci.c       | 2 +-
 xen/include/xen/vpci.h        | 2 ++
 5 files changed, 9 insertions(+), 21 deletions(-)

diff --git a/xen/arch/arm/xen.lds.S b/xen/arch/arm/xen.lds.S
index b773f91f1c..08016948ab 100644
--- a/xen/arch/arm/xen.lds.S
+++ b/xen/arch/arm/xen.lds.S
@@ -60,7 +60,7 @@ SECTIONS
        *(.proc.info)
        __proc_info_end = .;
 
-#if defined(CONFIG_HAS_VPCI) && defined(CONFIG_LATE_HWDOM)
+#ifdef CONFIG_HAS_VPCI
        . = ALIGN(POINTER_ALIGN);
        __start_vpci_array = .;
        *(SORT(.data.vpci.*))
@@ -189,13 +189,6 @@ SECTIONS
        *(.init_array)
        *(SORT(.init_array.*))
        __ctors_end = .;
-
-#if defined(CONFIG_HAS_VPCI) && !defined(CONFIG_LATE_HWDOM)
-       . = ALIGN(POINTER_ALIGN);
-       __start_vpci_array = .;
-       *(SORT(.data.vpci.*))
-       __end_vpci_array = .;
-#endif
   } :text
   __init_end_efi = .;
   . = ALIGN(STACK_SIZE);
diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index 11b1da2154..87e344d4dd 100644
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -134,7 +134,7 @@ SECTIONS
        *(.ex_table.pre)
        __stop___pre_ex_table = .;
 
-#if defined(CONFIG_HAS_VPCI) && defined(CONFIG_LATE_HWDOM)
+#ifdef CONFIG_HAS_VPCI
        . = ALIGN(POINTER_ALIGN);
        __start_vpci_array = .;
        *(SORT(.data.vpci.*))
@@ -247,13 +247,6 @@ SECTIONS
        *(.init_array)
        *(SORT(.init_array.*))
        __ctors_end = .;
-
-#if defined(CONFIG_HAS_VPCI) && !defined(CONFIG_LATE_HWDOM)
-       . = ALIGN(POINTER_ALIGN);
-       __start_vpci_array = .;
-       *(SORT(.data.vpci.*))
-       __end_vpci_array = .;
-#endif
   } PHDR(text)
 
   . = ALIGN(SECTION_ALIGN);
diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c
index 35e0190796..8928a1c07d 100644
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -756,10 +756,9 @@ int pci_add_device(u16 seg, u8 bus, u8 devfn,
     if ( !pdev->domain )
     {
         pdev->domain = hardware_domain;
-#ifdef CONFIG_ARM
         /*
-         * On ARM PCI devices discovery will be done by Dom0. Add vpci handler
-         * when Dom0 inform XEN to add the PCI devices in XEN.
+         * For devices not discovered by Xen during boot, add vPCI handlers
+         * when Dom0 first informs Xen about such devices.
          */
         ret = vpci_add_handlers(pdev);
         if ( ret )
@@ -768,10 +767,10 @@ int pci_add_device(u16 seg, u8 bus, u8 devfn,
             pdev->domain = NULL;
             goto out;
         }
-#endif
         ret = iommu_add_device(pdev);
         if ( ret )
         {
+            vpci_remove_device(pdev);
             pdev->domain = NULL;
             goto out;
         }
@@ -819,6 +818,7 @@ int pci_remove_device(u16 seg, u8 bus, u8 devfn)
     list_for_each_entry ( pdev, &pseg->alldevs_list, alldevs_list )
         if ( pdev->bus == bus && pdev->devfn == devfn )
         {
+            vpci_remove_device(pdev);
             pci_cleanup_msi(pdev);
             ret = iommu_remove_device(pdev);
             if ( pdev->domain )
diff --git a/xen/drivers/vpci/vpci.c b/xen/drivers/vpci/vpci.c
index decf7d87a1..74894bcbac 100644
--- a/xen/drivers/vpci/vpci.c
+++ b/xen/drivers/vpci/vpci.c
@@ -54,7 +54,7 @@ void vpci_remove_device(struct pci_dev *pdev)
     pdev->vpci = NULL;
 }
 
-int __hwdom_init vpci_add_handlers(struct pci_dev *pdev)
+int vpci_add_handlers(struct pci_dev *pdev)
 {
     unsigned int i;
     int rc = 0;
diff --git a/xen/include/xen/vpci.h b/xen/include/xen/vpci.h
index 6746c2589a..9ea66e033f 100644
--- a/xen/include/xen/vpci.h
+++ b/xen/include/xen/vpci.h
@@ -230,6 +230,8 @@ static inline int vpci_add_handlers(struct pci_dev *pdev)
     return 0;
 }
 
+static inline void vpci_remove_device(struct pci_dev *pdev) { }
+
 static inline void vpci_dump_msi(void) { }
 
 static inline uint32_t vpci_read(pci_sbdf_t sbdf, unsigned int reg,
-- 
2.25.1