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[Xen-devel] [PATCH v5 6/8] hvmloader: Load large devices into high MMIO space as needed

Keep track of how much mmio space is left total, as well as the amount
of "low" MMIO space (<4GiB), and only load devices into high memory if
there is not enough low memory for the rest of the devices to fit.

Because devices are processed by size in order from large to small,
this should preferentially relocate devices with large BARs to 64-bit

 - Just use mmio_total rather than introducing a new variable.
 - Port to using mem_resource directly rather than low_mmio_left

Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Acked-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
CC: Ian Campbell <ian.campbell@xxxxxxxxxx>
CC: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
CC: Hanweidong <hanweidong@xxxxxxxxxx>
CC: Keir Fraser <keir@xxxxxxx>
 tools/firmware/hvmloader/pci.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/firmware/hvmloader/pci.c b/tools/firmware/hvmloader/pci.c
index 1fe250d..68d4e44 100644
--- a/tools/firmware/hvmloader/pci.c
+++ b/tools/firmware/hvmloader/pci.c
@@ -271,6 +271,11 @@ void pci_setup(void)
         bar_sz  = bars[i].bar_sz;
+         * Relocate to high memory if the total amount of MMIO needed
+         * is more than the low MMIO available.  Because devices are
+         * processed in order of bar_sz, this will preferentially
+         * relocate larger devices to high memory first.
+         *
          * NB: The code here is rather fragile, as the check here to see
          * whether bar_sz will fit in the low MMIO region doesn't match the
          * real check made below, which involves aligning the base offset of 
@@ -284,7 +289,7 @@ void pci_setup(void)
          * Should either of those two conditions change, this code will break.
         using_64bar = bars[i].is_64bar && bar64_relocate
-            && (bar_sz > (mem_resource.max - mem_resource.base));
+            && (mmio_total > (mem_resource.max - mem_resource.base));
         bar_data = pci_readl(devfn, bar_reg);
         if ( (bar_data & PCI_BASE_ADDRESS_SPACE) ==
@@ -306,6 +311,7 @@ void pci_setup(void)
                 resource = &mem_resource;
                 bar_data &= ~PCI_BASE_ADDRESS_MEM_MASK;
+            mmio_total -= bar_sz;

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