[Qemu-devel] [PATCH 1/3] pc-bios: enable io/memory unconditionally

[Michael S. Tsirkin]

VGA adapters need to claim memory and i/o
transactions even if they do not have any
i/o or memory bars. E.g. PCI spec, page 297,
gives an example of such a device:

        Programming interface 0000 0000b
        VGA-compatible controller. Memory
        addresses 0A 0000h through 0B
        FFFFh. I/O addresses 3B0h to 3BBh
        and 3C0h to 3DFh and all aliases of
        these addresses.

While we could check for these devices and special-case them, it is
easier to fix this by enabling i/o and memory space unconditionally:
devices that do not support it will just ignore this setting.

Signed-off-by: Michael S. Tsirkin <address@hidden>
---
 kvm/bios/rombios32.c |   18 +++++++-----------
 1 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/kvm/bios/rombios32.c b/kvm/bios/rombios32.c
index 0b3556c..747a97b 100755
--- a/kvm/bios/rombios32.c
+++ b/kvm/bios/rombios32.c
@@ -700,6 +700,7 @@ void smp_probe(void)
 #define PCI_COMMAND            0x04    /* 16 bits */
 #define  PCI_COMMAND_IO                0x1     /* Enable response in I/O space 
*/
 #define  PCI_COMMAND_MEMORY    0x2     /* Enable response in Memory space */
+#define PCI_CLASS_PROG         0x09    /* Reg. Level Programming Interface */
 #define PCI_CLASS_DEVICE        0x0a    /* Device class */
 #define PCI_INTERRUPT_LINE     0x3c    /* 8 bits */
 #define PCI_INTERRUPT_PIN      0x3d    /* 8 bits */
@@ -767,7 +768,6 @@ static uint32_t pci_config_readb(PCIDevice *d, uint32_t 
addr)
 
 static void pci_set_io_region_addr(PCIDevice *d, int region_num, uint32_t addr)
 {
-    uint16_t cmd;
     uint32_t ofs, old_addr;
 
     if ( region_num == PCI_ROM_SLOT ) {
@@ -780,16 +780,6 @@ static void pci_set_io_region_addr(PCIDevice *d, int 
region_num, uint32_t addr)
 
     pci_config_writel(d, ofs, addr);
     BX_INFO("region %d: 0x%08x\n", region_num, addr);
-
-    /* enable memory mappings */
-    cmd = pci_config_readw(d, PCI_COMMAND);
-    if ( region_num == PCI_ROM_SLOT )
-        cmd |= 2;
-    else if (old_addr & PCI_ADDRESS_SPACE_IO)
-        cmd |= 1;
-    else
-        cmd |= 2;
-    pci_config_writew(d, PCI_COMMAND, cmd);
 }
 
 /* return the global irq number corresponding to a given device irq
@@ -946,6 +936,7 @@ static void pci_bios_init_device(PCIDevice *d)
 {
     int class;
     uint32_t *paddr;
+    uint16_t cmd;
     int i, pin, pic_irq, vendor_id, device_id;
 
     class = pci_config_readw(d, PCI_CLASS_DEVICE);
@@ -1024,6 +1015,11 @@ static void pci_bios_init_device(PCIDevice *d)
         break;
     }
 
+    /* enable memory mappings */
+    cmd = pci_config_readw(d, PCI_COMMAND);
+    cmd |= PCI_COMMAND_IO | PCI_COMMAND_MEMORY;
+    pci_config_writew(d, PCI_COMMAND, cmd);
+
     /* map the interrupt */
     pin = pci_config_readb(d, PCI_INTERRUPT_PIN);
     if (pin != 0) {
-- 
1.6.5.rc2