[PATCH v11 01/17] pci: msi: pass pdev to pci_enable_msi() function

[Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>]

Previously pci_enable_msi() function obtained pdev pointer by itself,
but taking into account upcoming changes to PCI locking, it is better
when caller passes already acquired pdev pointer to the function,
because caller knows better how to obtain the pointer and which locks
are needed to be used. Also, in most cases caller already has pointer
to pdev, so we can avoid an extra list walk.

Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>

---
In v11:
 - Made pdev parameter very first in pci_enable_msi() and friends.
 - Extended the commit message
 - Added check for pdev into ns16550 driver
 - Replaced hard tabs with spaces

Changes in v10:

 - New in v10. This is the result of discussion in "vpci: add initial
 support for virtual PCI bus topology"
---
 xen/arch/x86/include/asm/msi.h |  5 +++--
 xen/arch/x86/irq.c             |  2 +-
 xen/arch/x86/msi.c             | 19 ++++++++++---------
 xen/drivers/char/ns16550.c     | 28 ++++++++++++++++++----------
 4 files changed, 32 insertions(+), 22 deletions(-)

diff --git a/xen/arch/x86/include/asm/msi.h b/xen/arch/x86/include/asm/msi.h
index c1ece2786e..07b3ee55e9 100644
--- a/xen/arch/x86/include/asm/msi.h
+++ b/xen/arch/x86/include/asm/msi.h
@@ -81,8 +81,9 @@ struct irq_desc;
 struct hw_interrupt_type;
 struct msi_desc;
 /* Helper functions */
-extern int pci_enable_msi(struct msi_info *msi, struct msi_desc **desc);
-extern void pci_disable_msi(struct msi_desc *msi_desc);
+extern int pci_enable_msi(struct pci_dev *pdev, struct msi_info *msi,
+                          struct msi_desc **desc);
+extern void pci_disable_msi(struct msi_desc *desc);
 extern int pci_prepare_msix(u16 seg, u8 bus, u8 devfn, bool off);
 extern void pci_cleanup_msi(struct pci_dev *pdev);
 extern int setup_msi_irq(struct irq_desc *desc, struct msi_desc *msidesc);
diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
index 6e668b1b4f..50e49e1a4b 100644
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -2176,7 +2176,7 @@ int map_domain_pirq(
         if ( !pdev )
             goto done;
 
-        ret = pci_enable_msi(msi, &msi_desc);
+        ret = pci_enable_msi(pdev, msi, &msi_desc);
         if ( ret )
         {
             if ( ret > 0 )
diff --git a/xen/arch/x86/msi.c b/xen/arch/x86/msi.c
index 7f8e794254..335c0868a2 100644
--- a/xen/arch/x86/msi.c
+++ b/xen/arch/x86/msi.c
@@ -983,13 +983,13 @@ static int msix_capability_init(struct pci_dev *dev,
  * irq or non-zero for otherwise.
  **/
 
-static int __pci_enable_msi(struct msi_info *msi, struct msi_desc **desc)
+static int __pci_enable_msi(struct pci_dev *pdev, struct msi_info *msi,
+                            struct msi_desc **desc)
 {
-    struct pci_dev *pdev;
     struct msi_desc *old_desc;
 
     ASSERT(pcidevs_locked());
-    pdev = pci_get_pdev(NULL, msi->sbdf);
+
     if ( !pdev )
         return -ENODEV;
 
@@ -1038,13 +1038,13 @@ static void __pci_disable_msi(struct msi_desc *entry)
  * of irqs available. Driver should use the returned value to re-send
  * its request.
  **/
-static int __pci_enable_msix(struct msi_info *msi, struct msi_desc **desc)
+static int __pci_enable_msix(struct pci_dev *pdev, struct msi_info *msi,
+                             struct msi_desc **desc)
 {
-    struct pci_dev *pdev;
     struct msi_desc *old_desc;
 
     ASSERT(pcidevs_locked());
-    pdev = pci_get_pdev(NULL, msi->sbdf);
+
     if ( !pdev || !pdev->msix )
         return -ENODEV;
 
@@ -1151,15 +1151,16 @@ int pci_prepare_msix(u16 seg, u8 bus, u8 devfn, bool 
off)
  * Notice: only construct the msi_desc
  * no change to irq_desc here, and the interrupt is masked
  */
-int pci_enable_msi(struct msi_info *msi, struct msi_desc **desc)
+int pci_enable_msi(struct pci_dev *pdev, struct msi_info *msi,
+                   struct msi_desc **desc)
 {
     ASSERT(pcidevs_locked());
 
     if ( !use_msi )
         return -EPERM;
 
-    return msi->table_base ? __pci_enable_msix(msi, desc) :
-                             __pci_enable_msi(msi, desc);
+    return msi->table_base ? __pci_enable_msix(pdev, msi, desc) :
+                             __pci_enable_msi(pdev, msi, desc);
 }
 
 /*
diff --git a/xen/drivers/char/ns16550.c b/xen/drivers/char/ns16550.c
index ddf2a48be6..cfe9ff8d2a 100644
--- a/xen/drivers/char/ns16550.c
+++ b/xen/drivers/char/ns16550.c
@@ -452,21 +452,29 @@ static void __init cf_check ns16550_init_postirq(struct 
serial_port *port)
             if ( rc > 0 )
             {
                 struct msi_desc *msi_desc = NULL;
+                struct pci_dev *pdev;
 
                 pcidevs_lock();
 
-                rc = pci_enable_msi(&msi, &msi_desc);
-                if ( !rc )
+                pdev = pci_get_pdev(NULL, msi.sbdf);
+                if ( pdev )
                 {
-                    struct irq_desc *desc = irq_to_desc(msi.irq);
-                    unsigned long flags;
-
-                    spin_lock_irqsave(&desc->lock, flags);
-                    rc = setup_msi_irq(desc, msi_desc);
-                    spin_unlock_irqrestore(&desc->lock, flags);
-                    if ( rc )
-                        pci_disable_msi(msi_desc);
+                    rc = pci_enable_msi(pdev, &msi, &msi_desc);
+
+                    if ( !rc )
+                    {
+                        struct irq_desc *desc = irq_to_desc(msi.irq);
+                        unsigned long flags;
+
+                        spin_lock_irqsave(&desc->lock, flags);
+                        rc = setup_msi_irq(desc, msi_desc);
+                        spin_unlock_irqrestore(&desc->lock, flags);
+                        if ( rc )
+                            pci_disable_msi(msi_desc);
+                    }
                 }
+                else
+                    rc = -ENODEV;
 
                 pcidevs_unlock();
 
-- 
2.42.0