ALSA: intel8x0: improve virtual environment detection

Detection code improved by PCI SSID usage. VM optimization
now enabled only for known devcices (skip host devices forwarded
to VM by VT-d or same kind of technology).
For debug/troubleshooting purposes optimization can be
forced (on/off) by module parameter: "inside_vm" (boolean).

Known devices (PCI SSID):
1af4:1100: Reserved for KVM devices. Note this is not yet
           implemented for KVM's ICH/AC'97 emulation.
1ab8:xxxx: Parallels ICH/AC'97 emulated sound.

[ fixed a minor coding-style issue by tiwai]

Signed-off-by: Konstantin Ozerkov <kozerkov@parallels.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/pci/intel8x0.c b/sound/pci/intel8x0.c
index 2d4bb4c..11718b4 100644 (file)
--- a/sound/pci/intel8x0.c
+++ b/sound/pci/intel8x0.c
@@ -2937,20 +2937,41 @@ static unsigned int sis_codec_bits[3] = {
        ICH_PCR, ICH_SCR, ICH_SIS_TCR
 };
 
-static int __devinit snd_intel8x0_inside_vm(void)
+static int __devinit snd_intel8x0_inside_vm(struct pci_dev *pci)
 {
-       int result = inside_vm;
+       int result  = inside_vm;
+       char *msg   = NULL;
 
-       if (result < 0) {
-               /* detect KVM and Parallels virtual environments */
-               result = kvm_para_available();
-#if defined(__i386__) || defined(__x86_64__)
-               result = result || boot_cpu_has(X86_FEATURE_HYPERVISOR);
+       /* check module parameter first (override detection) */
+       if (result >= 0) {
+               msg = result ? "enable (forced) VM" : "disable (forced) VM";
+               goto fini;
+       }
+
+       /* detect KVM and Parallels virtual environments */
+       result = kvm_para_available();
+#ifdef X86_FEATURE_HYPERVISOR
+       result = result || boot_cpu_has(X86_FEATURE_HYPERVISOR);
 #endif
+       if (!result)
+               goto fini;
+
+       /* check for known (emulated) devices */
+       if (pci->subsystem_vendor == 0x1af4 &&
+           pci->subsystem_device == 0x1100) {
+               /* KVM emulated sound, PCI SSID: 1af4:1100 */
+               msg = "enable KVM";
+       } else if (pci->subsystem_vendor == 0x1ab8) {
+               /* Parallels VM emulated sound, PCI SSID: 1ab8:xxxx */
+               msg = "enable Parallels VM";
+       } else {
+               msg = "disable (unknown or VT-d) VM";
+               result = 0;
        }
 
-       if (result)
-               printk(KERN_INFO "intel8x0: enable KVM optimization\n");
+fini:
+       if (msg != NULL)
+               printk(KERN_INFO "intel8x0: %s optimization\n", msg);
 
        return result;
 }
@@ -3022,7 +3043,7 @@ static int __devinit snd_intel8x0_create(struct snd_card *card,
        if (xbox)
                chip->xbox = 1;
 
-       chip->inside_vm = snd_intel8x0_inside_vm();
+       chip->inside_vm = snd_intel8x0_inside_vm(pci);
 
        if (pci->vendor == PCI_VENDOR_ID_INTEL &&
            pci->device == PCI_DEVICE_ID_INTEL_440MX)