From 3abc66706385e08f7003ca746be005e4c2152b09 Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Tue, 12 Jan 2021 09:10:31 +0100 Subject: drm: Implement drm_need_swiotlb() in drm_cache.c MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The function is declared in drm_cache.h. I also removed the curly braces from the for loop to adhere to kernel coding style. Signed-off-by: Thomas Zimmermann Reviewed-by: Christian König Reviewed-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20210112081035.6882-3-tzimmermann@suse.de --- drivers/gpu/drm/drm_cache.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) (limited to 'drivers/gpu/drm/drm_cache.c') diff --git a/drivers/gpu/drm/drm_cache.c b/drivers/gpu/drm/drm_cache.c index 0fe3c496002a..49551a7fa22f 100644 --- a/drivers/gpu/drm/drm_cache.c +++ b/drivers/gpu/drm/drm_cache.c @@ -30,6 +30,7 @@ #include #include +#include #include @@ -176,3 +177,34 @@ drm_clflush_virt_range(void *addr, unsigned long length) #endif } EXPORT_SYMBOL(drm_clflush_virt_range); + +bool drm_need_swiotlb(int dma_bits) +{ + struct resource *tmp; + resource_size_t max_iomem = 0; + + /* + * Xen paravirtual hosts require swiotlb regardless of requested dma + * transfer size. + * + * NOTE: Really, what it requires is use of the dma_alloc_coherent + * allocator used in ttm_dma_populate() instead of + * ttm_populate_and_map_pages(), which bounce buffers so much in + * Xen it leads to swiotlb buffer exhaustion. + */ + if (xen_pv_domain()) + return true; + + /* + * Enforce dma_alloc_coherent when memory encryption is active as well + * for the same reasons as for Xen paravirtual hosts. + */ + if (mem_encrypt_active()) + return true; + + for (tmp = iomem_resource.child; tmp; tmp = tmp->sibling) + max_iomem = max(max_iomem, tmp->end); + + return max_iomem > ((u64)1 << dma_bits); +} +EXPORT_SYMBOL(drm_need_swiotlb); -- cgit v1.2.3