[PATCH 2/2] Improve legacy vbios handling

[Grzegorz Uriasz <gorbak25@gmail.com>]

Signed-off-by: Grzegorz Uriasz <gorbak25@gmail.com>
---
 hw/xen/xen_pt.c          |  8 +++++--
 hw/xen/xen_pt_graphics.c | 48 +++++++++++++++++++++++++++++++++++++---
 hw/xen/xen_pt_load_rom.c |  2 +-
 3 files changed, 52 insertions(+), 6 deletions(-)

diff --git a/hw/xen/xen_pt.c b/hw/xen/xen_pt.c
index b91082cb8b..ffc3559dd4 100644
--- a/hw/xen/xen_pt.c
+++ b/hw/xen/xen_pt.c
@@ -483,8 +483,12 @@ static int xen_pt_register_regions(XenPCIPassthroughState *s, uint16_t *cmd)
                    i, r->size, r->base_addr, type);
     }
 
-    /* Register expansion ROM address */
-    if (d->rom.base_addr && d->rom.size) {
+    /*
+     * Register expansion ROM address. If we are dealing with a ROM
+     * shadow copy for legacy vga devices then don't bother to map it
+     * as previous code creates a proper shadow copy
+     */
+    if (d->rom.base_addr && d->rom.size && !(is_igd_vga_passthrough(d))) {
         uint32_t bar_data = 0;
 
         /* Re-set BAR reported by OS, otherwise ROM can't be read. */
diff --git a/hw/xen/xen_pt_graphics.c b/hw/xen/xen_pt_graphics.c
index a3bc7e3921..fe0ef2685c 100644
--- a/hw/xen/xen_pt_graphics.c
+++ b/hw/xen/xen_pt_graphics.c
@@ -129,7 +129,7 @@ int xen_pt_unregister_vga_regions(XenHostPCIDevice *dev)
     return 0;
 }
 
-static void *get_vgabios(XenPCIPassthroughState *s, int *size,
+static void *get_sysfs_vgabios(XenPCIPassthroughState *s, int *size,
                        XenHostPCIDevice *dev)
 {
     return pci_assign_dev_load_option_rom(&s->dev, size,
@@ -137,6 +137,45 @@ static void *get_vgabios(XenPCIPassthroughState *s, int *size,
                                           dev->dev, dev->func);
 }
 
+static void xen_pt_direct_vbios_copy(XenPCIPassthroughState *s, Error **errp)
+{
+    int fd = -1;
+    void *guest_bios = NULL;
+    void *host_vbios = NULL;
+    /* This is always 32 pages in the real mode reserved region */
+    int bios_size = 32 << XC_PAGE_SHIFT;
+    int vbios_addr = 0xc0000;
+
+    fd = open("/dev/mem", O_RDONLY);
+    if (fd == -1) {
+        error_setg(errp, "Can't open /dev/mem: %s", strerror(errno));
+        return;
+    }
+    host_vbios = mmap(NULL, bios_size,
+            PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, fd, vbios_addr);
+    close(fd);
+
+    if (host_vbios == MAP_FAILED) {
+        error_setg(errp, "Failed to mmap host vbios: %s", strerror(errno));
+        return;
+    }
+
+    memory_region_init_ram(&s->dev.rom, OBJECT(&s->dev),
+            "legacy_vbios.rom", bios_size, &error_abort);
+    guest_bios = memory_region_get_ram_ptr(&s->dev.rom);
+    memcpy(guest_bios, host_vbios, bios_size);
+
+    if (munmap(host_vbios, bios_size) == -1) {
+        XEN_PT_LOG(&s->dev, "Failed to unmap host vbios: %s\n", strerror(errno));
+    }
+
+    cpu_physical_memory_write(vbios_addr, guest_bios, bios_size);
+    memory_region_set_address(&s->dev.rom, vbios_addr);
+    pci_register_bar(&s->dev, PCI_ROM_SLOT, PCI_BASE_ADDRESS_SPACE_MEMORY, &s->dev.rom);
+    s->dev.has_rom = true;
+    XEN_PT_LOG(&s->dev, "Legacy VBIOS registered\n");
+}
+
 /* Refer to Seabios. */
 struct rom_header {
     uint16_t signature;
@@ -179,9 +218,11 @@ void xen_pt_setup_vga(XenPCIPassthroughState *s, XenHostPCIDevice *dev,
         return;
     }
 
-    bios = get_vgabios(s, &bios_size, dev);
+    bios = get_sysfs_vgabios(s, &bios_size, dev);
     if (!bios) {
-        error_setg(errp, "VGA: Can't get VBIOS");
+        XEN_PT_LOG(&s->dev, "Unable to get host VBIOS from sysfs - "
+                            "falling back to a direct copy of memory ranges\n");
+        xen_pt_direct_vbios_copy(s, errp);
         return;
     }
 
@@ -223,6 +264,7 @@ void xen_pt_setup_vga(XenPCIPassthroughState *s, XenHostPCIDevice *dev,
 
     /* Currently we fixed this address as a primary for legacy BIOS. */
     cpu_physical_memory_write(0xc0000, bios, bios_size);
+    XEN_PT_LOG(&s->dev, "Legacy VBIOS registered\n");
 }
 
 uint32_t igd_read_opregion(XenPCIPassthroughState *s)
diff --git a/hw/xen/xen_pt_load_rom.c b/hw/xen/xen_pt_load_rom.c
index 9f100dc159..8cd9aa84dc 100644
--- a/hw/xen/xen_pt_load_rom.c
+++ b/hw/xen/xen_pt_load_rom.c
@@ -65,7 +65,7 @@ void *pci_assign_dev_load_option_rom(PCIDevice *dev,
         goto close_rom;
     }
 
-    pci_register_bar(dev, PCI_ROM_SLOT, 0, &dev->rom);
+    pci_register_bar(dev, PCI_ROM_SLOT, PCI_BASE_ADDRESS_SPACE_MEMORY, &dev->rom);
     dev->has_rom = true;
     *size = st.st_size;
 close_rom:
-- 
2.26.1