intel8x0 driver has the inside_vm check for skipping a buggy hardware workaround in the PCM pointer callback in the commit [228cf79376f1: ALSA: intel8x0: Improve performance in virtual environment]. This was originally applied to all devices on known VMs, but the code was switched to use the PCI ID matching for applying to only known devices (KVM and Parallels), in order to avoid applying wrongly to VT-d and other such cases, in the commit [7fb4f392bd27: ALSA: intel8x0: improve virtual environment detection].
Meanwhile, the original VM check was kept even after switching to the PCI ID matching. It was partly because we weren't 100% sure whether we had covered all well, and partly because this would help identifying the issue once when a user of another VM hit the same problem or a regression. Currently the VM check is used only for showing the kernel message that the VM-optimization isn't applied, and the VM check itself doesn't change the actual driver behavior at all.
Despite the relatively safe driver behavior, the code caught attention of developers badly and brought many confusion / misunderstanding. Since we've got neither regression nor enhancement report for other VMs for five years long, it's likely safe to drop this superfluous VM check now.
The module option is still kept, so if a user still needs to adjust, it can be applied as was.
Cc: Andy Lutomirski luto@amacapital.net Cc: Luis R. Rodriguez mcgrof@kernel.org Cc: Konstantin Ozerkov kozerkov@parallels.com Signed-off-by: Takashi Iwai tiwai@suse.de --- sound/pci/intel8x0.c | 20 +++----------------- 1 file changed, 3 insertions(+), 17 deletions(-)
diff --git a/sound/pci/intel8x0.c b/sound/pci/intel8x0.c index 8151318a69a2..9720a30dbfff 100644 --- a/sound/pci/intel8x0.c +++ b/sound/pci/intel8x0.c @@ -42,12 +42,6 @@ #include <asm/pgtable.h> #include <asm/cacheflush.h>
-#ifdef CONFIG_KVM_GUEST -#include <linux/kvm_para.h> -#else -#define kvm_para_available() (0) -#endif - MODULE_AUTHOR("Jaroslav Kysela perex@perex.cz"); MODULE_DESCRIPTION("Intel 82801AA,82901AB,i810,i820,i830,i840,i845,MX440; SiS 7012; Ali 5455"); MODULE_LICENSE("GPL"); @@ -2972,25 +2966,17 @@ static int snd_intel8x0_inside_vm(struct pci_dev *pci) 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 */ + result = 0; if (pci->subsystem_vendor == PCI_SUBVENDOR_ID_REDHAT_QUMRANET && pci->subsystem_device == PCI_SUBDEVICE_ID_QEMU) { /* KVM emulated sound, PCI SSID: 1af4:1100 */ msg = "enable KVM"; + result = 1; } 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; + result = 1; }
fini: