[Qemu-devel] [PATCH RFC 11/13] pc: pass PCI hole ranges to Guests

["Michael S. Tsirkin" <mst@redhat.com>]

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>
---
 hw/i386/pc.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 203c683..68d2610 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -997,6 +997,26 @@ static void pc_set_cpu_guest_info(CPUState *cpu, void *arg)
     }
 }
 
+/* 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 = 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;
@@ -1008,6 +1028,7 @@ 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,
-- 
MST