From: Vasilis Liaskovitis <vasilis.liaskovitis@profitbricks.com>

Initialize the 32-bit and 64-bit pci starting offsets from values passed in by
the qemu paravirt interface QEMU_CFG_PCI_WINDOW. Qemu calculates the starting
offsets based on initial memory and hotplug-able dimms.

It's possible to avoid the new paravirt interface, and calculate pci ranges from
srat entries. But the code changes are ugly, see:
http://lists.gnu.org/archive/html/qemu-devel/2012-09/msg03548.html

Signed-off-by: Vasilis Liaskovitis <vasilis.liaskovitis@profitbricks.com>
---
 src/paravirt.c | 7 +++++++
 src/paravirt.h | 1 +
 src/pciinit.c  | 9 +++++++++
 3 files changed, 17 insertions(+)

diff --git a/src/paravirt.c b/src/paravirt.c
index 5925c63..9c1e511 100644
--- a/src/paravirt.c
+++ b/src/paravirt.c
@@ -134,6 +134,7 @@ qemu_platform_setup(void)
 #define QEMU_CFG_BOOT_MENU              0x0e
 #define QEMU_CFG_MAX_CPUS               0x0f
 #define QEMU_CFG_FILE_DIR               0x19
+#define QEMU_CFG_PCI_WINDOW             0x1a
 #define QEMU_CFG_ARCH_LOCAL             0x8000
 #define QEMU_CFG_ACPI_TABLES            (QEMU_CFG_ARCH_LOCAL + 0)
 #define QEMU_CFG_SMBIOS_ENTRIES         (QEMU_CFG_ARCH_LOCAL + 1)
@@ -339,3 +340,9 @@ void qemu_cfg_init(void)
                          , 0, be32_to_cpu(qfile.size));
     }
 }
+
+void qemu_cfg_get_pci_offsets(u64 *pcimem_start, u64 *pcimem64_start)
+{
+    qemu_cfg_read_entry(pcimem_start, QEMU_CFG_PCI_WINDOW, sizeof(u64));
+    qemu_cfg_read((u8*)(pcimem64_start), sizeof(u64));
+}
diff --git a/src/paravirt.h b/src/paravirt.h
index fce5af9..2c37d0d 100644
--- a/src/paravirt.h
+++ b/src/paravirt.h
@@ -27,5 +27,6 @@ static inline int runningOnKVM(void) {
 void qemu_preinit(void);
 void qemu_platform_setup(void);
 void qemu_cfg_init(void);
+void qemu_cfg_get_pci_offsets(u64 *pcimem_start, u64 *pcimem64_start);

 #endif
diff --git a/src/pciinit.c b/src/pciinit.c
index 8370b96..7e63c5e 100644
--- a/src/pciinit.c
+++ b/src/pciinit.c
@@ -805,6 +805,7 @@ static void pci_bios_map_devices(struct pci_bus *busses)
 void
 pci_setup(void)
 {
+    u64 pv_pcimem_start, pv_pcimem64_start;
     if (!CONFIG_QEMU)
         return;

@@ -837,6 +838,14 @@ pci_setup(void)

     pci_bios_init_devices();

+    /* if qemu gives us other pci window values, it means there are hotplug-able
+     * dimms. Adjust accordingly */
+    qemu_cfg_get_pci_offsets(&pv_pcimem_start, &pv_pcimem64_start);
+    if (pv_pcimem_start > pcimem_start)
+        pcimem_start = pv_pcimem_start;
+    if (pv_pcimem64_start > pcimem64_start)
+        pcimem64_start = pv_pcimem64_start;
+
     free(busses);

     pci_enable_default_vga();
--
1.8.3.1