pc: pass PCI hole ranges to Guests

Guest currently has to jump through lots of hoops to guess the PCI hole
ranges.  It's fragile, and makes us change BIOS each time we add a new
chipset.  Let's report the window in a ROM file, to make BIOS do exactly
what QEMU intends.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 8af1e4e527..7c4794c0e8 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -989,6 +989,31 @@ void pc_cpus_init(const char *cpu_model, DeviceState *icc_bridge)
     }
 }
 
+/* pci-info ROM file. Little endian format */
+typedef struct PcRomPciInfo {
+    uint64_t w32_min;
+    uint64_t w32_max;
+    uint64_t w64_min;
+    uint64_t w64_max;
+} PcRomPciInfo;
+
+static void pc_fw_cfg_guest_info(PcGuestInfo *guest_info)
+{
+    PcRomPciInfo *info;
+    if (!guest_info->has_pci_info) {
+        return;
+    }
+
+    info = g_malloc(sizeof *info);
+    info->w32_min = cpu_to_le64(guest_info->pci_info.w32.begin);
+    info->w32_max = cpu_to_le64(guest_info->pci_info.w32.end);
+    info->w64_min = cpu_to_le64(guest_info->pci_info.w64.begin);
+    info->w64_max = cpu_to_le64(guest_info->pci_info.w64.end);
+    /* Pass PCI hole info to guest via a side channel.
+     * Required so guest PCI enumeration does the right thing. */
+    fw_cfg_add_file(guest_info->fw_cfg, "etc/pci-info", info, sizeof *info);
+}
+
 typedef struct PcGuestInfoState {
     PcGuestInfo info;
     Notifier machine_done;
@@ -1000,6 +1025,7 @@ void pc_guest_info_machine_done(Notifier *notifier, void *data)
     PcGuestInfoState *guest_info_state = container_of(notifier,
                                                       PcGuestInfoState,
                                                       machine_done);
+    pc_fw_cfg_guest_info(&guest_info_state->info);
 }
 
 PcGuestInfo *pc_guest_info_init(ram_addr_t below_4g_mem_size,