On Mon, 13 Jun 2016 15:45:20 -0400 Alex Deucher <alexdeucher@xxxxxxxxx> wrote: > When executing in a PCI passthrough based virtuzliation environment, the > hypervisor will usually attempt to send a PCIe bus reset signal to the > ASIC when the VM reboots. In this scenario, the card is not correctly > initialized, but we still consider it to be posted. Therefore, in a > passthrough based environemnt we should always post the card to guarantee > it is in a good state for driver initialization. > > Ported from amdgpu commit: > amdgpu: fix asic initialization for virtualized environments > > Cc: Andres Rodriguez <andres.rodriguez@xxxxxxx> > Cc: Alex Williamson <alex.williamson@xxxxxxxxxx> > Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > --- > drivers/gpu/drm/radeon/radeon_device.c | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+) Thanks, I expect it's an improvement, though it's always a bit disappointing when a driver starts modifying its behavior based on what might be a transient feature of the platform, in this case a hypervisor platform. For instance, why does our bus reset and video ROM execution result in a different state than a physical BIOS doing the same? Can't this condition occur regardless of a hypervisor, perhaps a rare hot-add of a GPU, a bare metal kexec reboot, or perhaps simply a system BIOS optimized to post a limited set of devices. Detection based on some state of the device rather than an expectation based on what the device is running on seems preferable. I suspect Andres' patch for amdgpu only affects newer devices, which pretty much all suffer reset issues, at least under QEMU/VFIO, but I wonder how this patch affects existing working devices, like 6, 7, and some 8-series. Anyway, if this is the solution to the poor behavior we've seen with assigned AMD cards, maybe someone could request the same for the closed drivers, including Windows. Thanks, Alex > diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c > index e61c763..21c44b2 100644 > --- a/drivers/gpu/drm/radeon/radeon_device.c > +++ b/drivers/gpu/drm/radeon/radeon_device.c > @@ -630,6 +630,23 @@ void radeon_gtt_location(struct radeon_device *rdev, struct radeon_mc *mc) > /* > * GPU helpers function. > */ > + > +/** > + * radeon_device_is_virtual - check if we are running is a virtual environment > + * > + * Check if the asic has been passed through to a VM (all asics). > + * Used at driver startup. > + * Returns true if virtual or false if not. > + */ > +static bool radeon_device_is_virtual(void) > +{ > +#ifdef CONFIG_X86 > + return boot_cpu_has(X86_FEATURE_HYPERVISOR); > +#else > + return false; > +#endif > +} > + > /** > * radeon_card_posted - check if the hw has already been initialized > * > @@ -643,6 +660,10 @@ bool radeon_card_posted(struct radeon_device *rdev) > { > uint32_t reg; > > + /* for pass through, always force asic_init */ > + if (radeon_device_is_virtual()) > + return false; > + > /* required for EFI mode on macbook2,1 which uses an r5xx asic */ > if (efi_enabled(EFI_BOOT) && > (rdev->pdev->subsystem_vendor == PCI_VENDOR_ID_APPLE) && -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html