Patch "drm/radeon: fix asic initialization for virtualized environments" has been added to the 4.6-stable tree

This is a note to let you know that I've just added the patch titled

drm/radeon: fix asic initialization for virtualized environments

to the 4.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-radeon-fix-asic-initialization-for-virtualized-environments.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Alex Deucher <[email protected]>
Date: Mon, 13 Jun 2016 15:37:34 -0400
Subject: drm/radeon: fix asic initialization for virtualized environments

From: Alex Deucher <[email protected]>

commit 05082b8bbd1a0ffc74235449c4b8930a8c240f85 upstream.

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

---
 drivers/gpu/drm/radeon/radeon_device.c |   21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

@@ -630,6 +630,23 @@ void radeon_gtt_location(struct radeon_d
 /*
  * 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_de
 {
 	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) &&

Patches currently in stable-queue which might be from [email protected] are

queue-4.6/drm-radeon-fix-asic-initialization-for-virtualized-environments.patch queue-4.6/drm-amd-powerplay-fix-logic-error.patch queue-4.6/drm-amdgpu-gfx7-fix-broken-condition-check.patch queue-4.6/drm-amdgpu-initialize-amdgpu_cgs_acpi_eval_object-result-value.patch queue-4.6/drm-amd-powerplay-fix-bug-that-function-parameter-was-incorect.patch queue-4.6/drm-dp-mst-always-clear-proposed-vcpi-table-for-port.patch queue-4.6/drm-amd-powerplay-need-to-notify-system-bios-pcie-device-ready.patch queue-4.6/drm-amd-powerplay-incorrectly-use-of-the-function-return-value.patch queue-4.6/drm-amdgpu-fix-num_rbs-exposed-to-userspace-v2.patch queue-4.6/drm-amd-powerplay-fix-incorrect-voltage-table-value-for-tonga.patch