1 files changed, 47 insertions, 11 deletions

diff --git a/sound/pci/intel8x0.c b/sound/pci/intel8x0.c
index 29e312597f20..11718b49b2e2 100644
--- a/sound/pci/intel8x0.c
+++ b/sound/pci/intel8x0.c
@@ -1077,6 +1077,13 @@ static snd_pcm_uframes_t snd_intel8x0_pcm_pointer(struct snd_pcm_substream *subs
                 }
                 if (civ != igetbyte(chip, ichdev->reg_offset + ICH_REG_OFF_CIV))
                         continue;
+
+                /* IO read operation is very expensive inside virtual machine
+                 * as it is emulated. The probability that subsequent PICB read
+                 * will return different result is high enough to loop till
+                 * timeout here.
+                 * Same CIV is strict enough condition to be sure that PICB
+                 * is valid inside VM on emulated card. */
                 if (chip->inside_vm)
                         break;
                 if (ptr1 == igetword(chip, ichdev->reg_offset + ichdev->roff_picb))
@@ -2930,6 +2937,45 @@ static unsigned int sis_codec_bits[3] = {
         ICH_PCR, ICH_SCR, ICH_SIS_TCR
 };
 
+static int __devinit snd_intel8x0_inside_vm(struct pci_dev *pci)
+{
+        int result  = inside_vm;
+        char *msg   = NULL;
+
+        /* 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;
+        }
+
+fini:
+        if (msg != NULL)
+                printk(KERN_INFO "intel8x0: %s optimization\n", msg);
+
+        return result;
+}
+
 static int __devinit snd_intel8x0_create(struct snd_card *card,
                                          struct pci_dev *pci,
                                          unsigned long device_type,
@@ -2997,9 +3043,7 @@ static int __devinit snd_intel8x0_create(struct snd_card *card,
         if (xbox)
                 chip->xbox = 1;
 
-        chip->inside_vm = inside_vm;
-        if (inside_vm)
-                printk(KERN_INFO "intel8x0: enable KVM optimization\n");
+        chip->inside_vm = snd_intel8x0_inside_vm(pci);
 
         if (pci->vendor == PCI_VENDOR_ID_INTEL &&
             pci->device == PCI_DEVICE_ID_INTEL_440MX)
@@ -3243,14 +3287,6 @@ static int __devinit snd_intel8x0_probe(struct pci_dev *pci,
                         buggy_irq = 0;
         }
 
-        if (inside_vm < 0) {
-                /* detect KVM and Parallels virtual environments */
-                inside_vm = kvm_para_available();
-#if defined(__i386__) || defined(__x86_64__)
-                inside_vm = inside_vm || boot_cpu_has(X86_FEATURE_HYPERVISOR);
-#endif
-        }
-
         if ((err = snd_intel8x0_create(card, pci, pci_id->driver_data,
                                        &chip)) < 0) {
                 snd_card_free(card);