[Xen-devel] [PATCH v2] tools/hvmloader: Use base instead of pci_mem_start for find_next_rmrr()

[Xiong Zhang <xiong.y.zhang@xxxxxxxxx>]

find_next_rmrr(base) is used to find the lowest RMRR ending above base
but below 4G. Current method couldn't cover the following situation:
a. two rmrr exist, small gap between them
b. pci_mem_start and mem_resource.base is below the first rmrr.base
c. find_next_rmrr(pci_mem_start) will find the first rmrr
d. After aligning mem_resource.base to bar size,
   first_rmrr.end < new_base < second_rmrr.base and
   new_base + bar_sz > second_rmrr.base.
   So the new bar will overlap with the second rmrr and doesn't overlap
with the first rmrr.
But the next_rmrr point to the first rmrr, then check_overlap() couldn't
find the overlap. Finally assign a wrong address to bar.

This patch using aligned new base to find the next rmrr, could fix the
above case and find all the overlapped rmrr with new base.

Signed-off-by: Xiong Zhang <xiong.y.zhang@xxxxxxxxx>

---
Changes since v1:
 - Reduce the scope of next_rmrr to just this if()
---
 tools/firmware/hvmloader/pci.c | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/tools/firmware/hvmloader/pci.c b/tools/firmware/hvmloader/pci.c
index f4288a3..1858d7f 100644
--- a/tools/firmware/hvmloader/pci.c
+++ b/tools/firmware/hvmloader/pci.c
@@ -84,7 +84,6 @@ void pci_setup(void)
     uint32_t vga_devfn = 256;
     uint16_t class, vendor_id, device_id;
     unsigned int bar, pin, link, isa_irq;
-    int next_rmrr;
 
     /* Resources assignable to PCI devices via BARs. */
     struct resource {
@@ -405,8 +404,6 @@ void pci_setup(void)
     io_resource.base = 0xc000;
     io_resource.max = 0x10000;
 
-    next_rmrr = find_next_rmrr(pci_mem_start);
-
     /* Assign iomem and ioport resources in descending order of size. */
     for ( i = 0; i < nr_bars; i++ )
     {
@@ -464,15 +461,21 @@ void pci_setup(void)
         base = (resource->base  + bar_sz - 1) & ~(uint64_t)(bar_sz - 1);
 
         /* If we're using mem_resource, check for RMRR conflicts. */
-        while ( resource == &mem_resource &&
-                next_rmrr >= 0 &&
-                check_overlap(base, bar_sz,
-                              memory_map.map[next_rmrr].addr,
-                              memory_map.map[next_rmrr].size) )
+        if ( resource == &mem_resource)
         {
-            base = memory_map.map[next_rmrr].addr + 
memory_map.map[next_rmrr].size;
-            base = (base + bar_sz - 1) & ~(bar_sz - 1);
+            int next_rmrr;
+
             next_rmrr = find_next_rmrr(base);
+            while ( next_rmrr >= 0 &&
+                    check_overlap(base, bar_sz,
+                              memory_map.map[next_rmrr].addr,
+                              memory_map.map[next_rmrr].size) )
+            {
+                base = memory_map.map[next_rmrr].addr +
+                       memory_map.map[next_rmrr].size;
+                base = (base + bar_sz - 1) & ~(bar_sz - 1);
+                next_rmrr = find_next_rmrr(base);
+            }
         }
 
         bar_data |= (uint32_t)base;
-- 
2.7.4


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