[PATCH v6 08/13] vpci/header: program p2m with guest BAR view

[Oleksandr Andrushchenko <andr2000@gmail.com>]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

Take into account guest's BAR view and program its p2m accordingly:
gfn is guest's view of the BAR and mfn is the physical BAR value as set
up by the PCI bus driver in the hardware domain.
This way hardware domain sees physical BAR values and guest sees
emulated ones.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
---
Since v5:
- remove debug print in map_range callback
- remove "identity" from the debug print
Since v4:
- moved start_{gfn|mfn} calculation into map_range
- pass vpci_bar in the map_data instead of start_{gfn|mfn}
- s/guest_addr/guest_reg
Since v3:
- updated comment (Roger)
- removed gfn_add(map->start_gfn, rc); which is wrong
- use v->domain instead of v->vpci.pdev->domain
- removed odd e.g. in comment
- s/d%d/%pd in altered code
- use gdprintk for map/unmap logs
Since v2:
- improve readability for data.start_gfn and restructure ?: construct
Since v1:
 - s/MSI/MSI-X in comments
---
 xen/drivers/vpci/header.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/xen/drivers/vpci/header.c b/xen/drivers/vpci/header.c
index 0c94504b87d8..88ca1ad8211d 100644
--- a/xen/drivers/vpci/header.c
+++ b/xen/drivers/vpci/header.c
@@ -30,6 +30,7 @@
 
 struct map_data {
     struct domain *d;
+    const struct vpci_bar *bar;
     bool map;
 };
 
@@ -41,8 +42,21 @@ static int map_range(unsigned long s, unsigned long e, void *data,
 
     for ( ; ; )
     {
+        /* Start address of the BAR as seen by the guest. */
+        gfn_t start_gfn = _gfn(PFN_DOWN(is_hardware_domain(map->d)
+                                        ? map->bar->addr
+                                        : map->bar->guest_reg));
+        /* Physical start address of the BAR. */
+        mfn_t start_mfn = _mfn(PFN_DOWN(map->bar->addr));
         unsigned long size = e - s + 1;
 
+        /*
+         * Ranges to be mapped don't always start at the BAR start address, as
+         * there can be holes or partially consumed ranges. Account for the
+         * offset of the current address from the BAR start.
+         */
+        start_gfn = gfn_add(start_gfn, s - mfn_x(start_mfn));
+
         /*
          * ARM TODOs:
          * - On ARM whether the memory is prefetchable or not should be passed
@@ -52,8 +66,8 @@ static int map_range(unsigned long s, unsigned long e, void *data,
          * - {un}map_mmio_regions doesn't support preemption.
          */
 
-        rc = map->map ? map_mmio_regions(map->d, _gfn(s), size, _mfn(s))
-                      : unmap_mmio_regions(map->d, _gfn(s), size, _mfn(s));
+        rc = map->map ? map_mmio_regions(map->d, start_gfn, size, _mfn(s))
+                      : unmap_mmio_regions(map->d, start_gfn, size, _mfn(s));
         if ( rc == 0 )
         {
             *c += size;
@@ -62,8 +76,8 @@ static int map_range(unsigned long s, unsigned long e, void *data,
         if ( rc < 0 )
         {
             printk(XENLOG_G_WARNING
-                   "Failed to identity %smap [%lx, %lx] for d%d: %d\n",
-                   map->map ? "" : "un", s, e, map->d->domain_id, rc);
+                   "Failed to %smap [%lx, %lx] for %pd: %d\n",
+                   map->map ? "" : "un", s, e, map->d, rc);
             break;
         }
         ASSERT(rc < size);
@@ -154,6 +168,7 @@ bool vpci_process_pending(struct vcpu *v)
             if ( rangeset_is_empty(bar->mem) )
                 continue;
 
+            data.bar = bar;
             rc = rangeset_consume_ranges(bar->mem, map_range, &data);
 
             if ( rc == -ERESTART )
@@ -206,6 +221,7 @@ static int __init apply_map(struct domain *d, const struct pci_dev *pdev,
         if ( rangeset_is_empty(bar->mem) )
             continue;
 
+        data.bar = bar;
         while ( (rc = rangeset_consume_ranges(bar->mem, map_range,
                                               &data)) == -ERESTART )
             process_pending_softirqs();
-- 
2.25.1