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		913b2cb727
		
	
	
	
	
		
			
			This commit fixes DRM failures on Xen PV systems that were introduced in v4.17 by the following commits:82626363drm: add func to get max iomem address v2fd5fd480drm/amdgpu: only enable swiotlb alloc when need v21bc3d3ccdrm/radeon: only enable swiotlb path when need v2 The introduction of ->need_swiotlb to the ttm_dma_populate() conditionals in the radeon and amdgpu device drivers causes Gnome to immediately crash on Xen PV systems, returning the user to the login screen. The following kernel errors get logged: [ 28.554259] radeon_dp_aux_transfer_native: 200 callbacks suppressed [ 31.219821] radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes) [ 31.220030] [drm:radeon_gem_object_create [radeon]] *ERROR* Failed to allocate GEM object (16384000, 2, 4096, -14) [ 31.226109] radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes) [ 31.226300] [drm:radeon_gem_object_create [radeon]] *ERROR* Failed to allocate GEM object (16384000, 2, 4096, -14) [ 31.300734] gnome-shell[1935]: segfault at 88 ip 00007f39151cd904 sp 00007ffc97611ad8 error 4 in libmutter-cogl.so[7f3915178000+aa000] [ 31.300745] Code: 5f c3 0f 1f 40 00 48 8b 47 78 48 8b 40 40 ff e0 66 0f 1f 44 00 00 48 8b 47 78 48 8b 40 48 ff e0 66 0f 1f 44 00 00 48 8b 47 78 <48> 8b 80 88 00 00 00 ff e0 0f 1f 00 48 8b 47 78 48 8b 40 68 ff e0 [ 38.193302] radeon_dp_aux_transfer_native: 116 callbacks suppressed [ 40.009317] radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes) [ 40.009488] [drm:radeon_gem_object_create [radeon]] *ERROR* Failed to allocate GEM object (16384000, 2, 4096, -14) [ 40.015114] radeon 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes) [ 40.015297] [drm:radeon_gem_object_create [radeon]] *ERROR* Failed to allocate GEM object (16384000, 2, 4096, -14) [ 40.028302] gnome-shell[2431]: segfault at 2dadf40 ip 0000000002dadf40 sp 00007ffcd24ea5f8 error 15 [ 40.028306] Code: 20 6e 31 00 00 00 00 00 00 00 00 37 e3 3d 2d 7f 00 00 80 f4 e6 3d 2d 7f 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 <00> 00 00 00 00 00 00 00 c1 00 00 00 00 00 00 00 80 e1 d2 03 00 00 This commit renames drm_get_max_iomem() to drm_need_swiotlb(), adds a xen_pv_domain() check to it, and moves the bit shifting comparison that always follows its usage into the function (simplifying the drm driver code). Signed-off-by: Michael D Labriola <michael.d.labriola@gmail.com> Reviewed-by: Christian König <christian.koenig@amd.com> Signed-off-by: Christian König <christian.koenig@amd.com> Link: https://patchwork.freedesktop.org/patch/286987/
		
			
				
	
	
		
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			73 lines
		
	
	
	
		
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| /**************************************************************************
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|  *
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|  * Copyright 2009 Red Hat Inc.
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|  * All Rights Reserved.
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|  *
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|  * Permission is hereby granted, free of charge, to any person obtaining a
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|  * copy of this software and associated documentation files (the
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|  * "Software"), to deal in the Software without restriction, including
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|  * without limitation the rights to use, copy, modify, merge, publish,
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|  * distribute, sub license, and/or sell copies of the Software, and to
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|  * permit persons to whom the Software is furnished to do so, subject to
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|  * the following conditions:
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|  *
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|  * The above copyright notice and this permission notice (including the
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|  * next paragraph) shall be included in all copies or substantial portions
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|  * of the Software.
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|  *
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|  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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|  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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|  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
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|  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
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|  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
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|  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
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|  * USE OR OTHER DEALINGS IN THE SOFTWARE.
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|  *
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|  *
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|  **************************************************************************/
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| /*
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|  * Authors:
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|  * Dave Airlie <airlied@redhat.com>
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|  */
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| 
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| #ifndef _DRM_CACHE_H_
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| #define _DRM_CACHE_H_
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| 
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| #include <linux/scatterlist.h>
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| 
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| void drm_clflush_pages(struct page *pages[], unsigned long num_pages);
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| void drm_clflush_sg(struct sg_table *st);
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| void drm_clflush_virt_range(void *addr, unsigned long length);
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| bool drm_need_swiotlb(int dma_bits);
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| 
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| 
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| static inline bool drm_arch_can_wc_memory(void)
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| {
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| #if defined(CONFIG_PPC) && !defined(CONFIG_NOT_COHERENT_CACHE)
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| 	return false;
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| #elif defined(CONFIG_MIPS) && defined(CONFIG_CPU_LOONGSON3)
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| 	return false;
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| #elif defined(CONFIG_ARM) || defined(CONFIG_ARM64)
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| 	/*
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| 	 * The DRM driver stack is designed to work with cache coherent devices
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| 	 * only, but permits an optimization to be enabled in some cases, where
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| 	 * for some buffers, both the CPU and the GPU use uncached mappings,
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| 	 * removing the need for DMA snooping and allocation in the CPU caches.
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| 	 *
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| 	 * The use of uncached GPU mappings relies on the correct implementation
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| 	 * of the PCIe NoSnoop TLP attribute by the platform, otherwise the GPU
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| 	 * will use cached mappings nonetheless. On x86 platforms, this does not
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| 	 * seem to matter, as uncached CPU mappings will snoop the caches in any
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| 	 * case. However, on ARM and arm64, enabling this optimization on a
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| 	 * platform where NoSnoop is ignored results in loss of coherency, which
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| 	 * breaks correct operation of the device. Since we have no way of
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| 	 * detecting whether NoSnoop works or not, just disable this
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| 	 * optimization entirely for ARM and arm64.
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| 	 */
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| 	return false;
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| #else
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| 	return true;
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| #endif
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| }
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| 
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| #endif
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