xen: Xen PCI platform device driver.

Add the xen pci platform device driver that is responsible
for initializing the grant table and xenbus in PV on HVM mode.
Few changes to xenbus and grant table are necessary to allow the delayed
initialization in HVM mode.
Grant table needs few additional modifications to work in HVM mode.

The Xen PCI platform device raises an irq every time an event has been
delivered to us. However these interrupts are only delivered to vcpu 0.
The Xen PCI platform interrupt handler calls xen_hvm_evtchn_do_upcall
that is a little wrapper around __xen_evtchn_do_upcall, the traditional
Xen upcall handler, the very same used with traditional PV guests.

When running on HVM the event channel upcall is never called while in
progress because it is a normal Linux irq handler (and we cannot switch
the irq chip wholesale to the Xen PV ones as we are running QEMU and
might have passed in PCI devices), therefore we cannot be sure that
evtchn_upcall_pending is 0 when returning.
For this reason if evtchn_upcall_pending is set by Xen we need to loop
again on the event channels set pending otherwise we might loose some
event channel deliveries.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

1 files changed, 67 insertions, 10 deletions

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index f66db3b91d61..6c4531816496 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -37,11 +37,13 @@
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/uaccess.h>
+#include <linux/io.h>
 
 #include <xen/xen.h>
 #include <xen/interface/xen.h>
 #include <xen/page.h>
 #include <xen/grant_table.h>
+#include <xen/interface/memory.h>
 #include <asm/xen/hypercall.h>
 
 #include <asm/pgtable.h>
@@ -59,6 +61,8 @@ static unsigned int boot_max_nr_grant_frames;
 static int gnttab_free_count;
 static grant_ref_t gnttab_free_head;
 static DEFINE_SPINLOCK(gnttab_list_lock);
+unsigned long xen_hvm_resume_frames;
+EXPORT_SYMBOL_GPL(xen_hvm_resume_frames);
 
 static struct grant_entry *shared;
 
@@ -433,7 +437,7 @@ static unsigned int __max_nr_grant_frames(void)
         return query.max_nr_frames;
 }
 
-static inline unsigned int max_nr_grant_frames(void)
+unsigned int gnttab_max_grant_frames(void)
 {
         unsigned int xen_max = __max_nr_grant_frames();
 
@@ -441,6 +445,7 @@ static inline unsigned int max_nr_grant_frames(void)
                 return boot_max_nr_grant_frames;
         return xen_max;
 }
+EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
 
 static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
 {
@@ -449,6 +454,30 @@ static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
         unsigned int nr_gframes = end_idx + 1;
         int rc;
 
+        if (xen_hvm_domain()) {
+                struct xen_add_to_physmap xatp;
+                unsigned int i = end_idx;
+                rc = 0;
+                /*
+                 * Loop backwards, so that the first hypercall has the largest
+                 * index, ensuring that the table will grow only once.
+                 */
+                do {
+                        xatp.domid = DOMID_SELF;
+                        xatp.idx = i;
+                        xatp.space = XENMAPSPACE_grant_table;
+                        xatp.gpfn = (xen_hvm_resume_frames >> PAGE_SHIFT) + i;
+                        rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
+                        if (rc != 0) {
+                                printk(KERN_WARNING
+                                                "grant table add_to_physmap failed, err=%d\n", rc);
+                                break;
+                        }
+                } while (i-- > start_idx);
+
+                return rc;
+        }
+
         frames = kmalloc(nr_gframes * sizeof(unsigned long), GFP_ATOMIC);
         if (!frames)
                 return -ENOMEM;
@@ -465,7 +494,7 @@ static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
 
         BUG_ON(rc || setup.status);
 
-        rc = arch_gnttab_map_shared(frames, nr_gframes, max_nr_grant_frames(),
+        rc = arch_gnttab_map_shared(frames, nr_gframes, gnttab_max_grant_frames(),
                                     &shared);
         BUG_ON(rc);
 
@@ -476,9 +505,27 @@ static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
 
 int gnttab_resume(void)
 {
-        if (max_nr_grant_frames() < nr_grant_frames)
+        unsigned int max_nr_gframes;
+
+        max_nr_gframes = gnttab_max_grant_frames();
+        if (max_nr_gframes < nr_grant_frames)
                 return -ENOSYS;
-        return gnttab_map(0, nr_grant_frames - 1);
+
+        if (xen_pv_domain())
+                return gnttab_map(0, nr_grant_frames - 1);
+
+        if (!shared) {
+                shared = ioremap(xen_hvm_resume_frames, PAGE_SIZE * max_nr_gframes);
+                if (shared == NULL) {
+                        printk(KERN_WARNING
+                                        "Failed to ioremap gnttab share frames!");
+                        return -ENOMEM;
+                }
+        }
+
+        gnttab_map(0, nr_grant_frames - 1);
+
+        return 0;
 }
 
 int gnttab_suspend(void)
@@ -495,7 +542,7 @@ static int gnttab_expand(unsigned int req_entries)
         cur = nr_grant_frames;
         extra = ((req_entries + (GREFS_PER_GRANT_FRAME-1)) /
                  GREFS_PER_GRANT_FRAME);
-        if (cur + extra > max_nr_grant_frames())
+        if (cur + extra > gnttab_max_grant_frames())
                 return -ENOSPC;
 
         rc = gnttab_map(cur, cur + extra - 1);
@@ -505,15 +552,12 @@ static int gnttab_expand(unsigned int req_entries)
         return rc;
 }
 
-static int __devinit gnttab_init(void)
+int gnttab_init(void)
 {
         int i;
         unsigned int max_nr_glist_frames, nr_glist_frames;
         unsigned int nr_init_grefs;
 
-        if (!xen_domain())
-                return -ENODEV;
-
         nr_grant_frames = 1;
         boot_max_nr_grant_frames = __max_nr_grant_frames();
 
@@ -556,5 +600,18 @@ static int __devinit gnttab_init(void)
         kfree(gnttab_list);
         return -ENOMEM;
 }
+EXPORT_SYMBOL_GPL(gnttab_init);
+
+static int __devinit __gnttab_init(void)
+{
+        /* Delay grant-table initialization in the PV on HVM case */
+        if (xen_hvm_domain())
+                return 0;
+
+        if (!xen_pv_domain())
+                return -ENODEV;
+
+        return gnttab_init();
+}
 
-core_initcall(gnttab_init);
+core_initcall(__gnttab_init);