1 files changed, 197 insertions, 20 deletions

diff --git a/drivers/gpu/drm/drm_cache.c b/drivers/gpu/drm/drm_cache.c
index 3bd76e918b5d..ea1d2d5d2c66 100644
--- a/drivers/gpu/drm/drm_cache.c
+++ b/drivers/gpu/drm/drm_cache.c
@@ -27,12 +27,18 @@
 /*
  * Authors: Thomas Hellström <thomas-at-tungstengraphics-dot-com>
  */
-
+#include <linux/cc_platform.h>
 #include <linux/export.h>
 #include <linux/highmem.h>
+#include <linux/ioport.h>
+#include <linux/iosys-map.h>
+#include <xen/xen.h>
 
 #include <drm/drm_cache.h>
 
+/* A small bounce buffer that fits on the stack. */
+#define MEMCPY_BOUNCE_SIZE 128
+
 #if defined(CONFIG_X86)
 #include <asm/smp.h>
 
@@ -62,10 +68,10 @@ static void drm_cache_flush_clflush(struct page *pages[],
 {
 	unsigned long i;
 
-	mb();
+	mb(); /*Full memory barrier used before so that CLFLUSH is ordered*/
 	for (i = 0; i < num_pages; i++)
 		drm_clflush_page(*pages++);
-	mb();
+	mb(); /*Also used after CLFLUSH so that all cache is flushed*/
 }
 #endif
 
@@ -87,11 +93,11 @@ drm_clflush_pages(struct page *pages[], unsigned long num_pages)
 		return;
 	}
 
-	if (wbinvd_on_all_cpus())
-		pr_err("Timed out waiting for cache flush\n");
+	wbinvd_on_all_cpus();
 
 #elif defined(__powerpc__)
 	unsigned long i;
+
 	for (i = 0; i < num_pages; i++) {
 		struct page *page = pages[i];
 		void *page_virtual;
@@ -105,8 +111,7 @@ drm_clflush_pages(struct page *pages[], unsigned long num_pages)
 		kunmap_atomic(page_virtual);
 	}
 #else
-	pr_err("Architecture has no drm_cache.c support\n");
-	WARN_ON_ONCE(1);
+	WARN_ONCE(1, "Architecture has no drm_cache.c support\n");
 #endif
 }
 EXPORT_SYMBOL(drm_clflush_pages);
@@ -125,19 +130,17 @@ drm_clflush_sg(struct sg_table *st)
 	if (static_cpu_has(X86_FEATURE_CLFLUSH)) {
 		struct sg_page_iter sg_iter;
 
-		mb();
-		for_each_sg_page(st->sgl, &sg_iter, st->nents, 0)
+		mb(); /*CLFLUSH is ordered only by using memory barriers*/
+		for_each_sgtable_page(st, &sg_iter, 0)
 			drm_clflush_page(sg_page_iter_page(&sg_iter));
-		mb();
+		mb(); /*Make sure that all cache line entry is flushed*/
 
 		return;
 	}
 
-	if (wbinvd_on_all_cpus())
-		pr_err("Timed out waiting for cache flush\n");
+	wbinvd_on_all_cpus();
 #else
-	pr_err("Architecture has no drm_cache.c support\n");
-	WARN_ON_ONCE(1);
+	WARN_ONCE(1, "Architecture has no drm_cache.c support\n");
 #endif
 }
 EXPORT_SYMBOL(drm_clflush_sg);
@@ -157,20 +160,194 @@ drm_clflush_virt_range(void *addr, unsigned long length)
 	if (static_cpu_has(X86_FEATURE_CLFLUSH)) {
 		const int size = boot_cpu_data.x86_clflush_size;
 		void *end = addr + length;
+
 		addr = (void *)(((unsigned long)addr) & -size);
-		mb();
+		mb(); /*CLFLUSH is only ordered with a full memory barrier*/
 		for (; addr < end; addr += size)
 			clflushopt(addr);
 		clflushopt(end - 1); /* force serialisation */
-		mb();
+		mb(); /*Ensure that every data cache line entry is flushed*/
 		return;
 	}
 
-	if (wbinvd_on_all_cpus())
-		pr_err("Timed out waiting for cache flush\n");
+	wbinvd_on_all_cpus();
 #else
-	pr_err("Architecture has no drm_cache.c support\n");
-	WARN_ON_ONCE(1);
+	WARN_ONCE(1, "Architecture has no drm_cache.c support\n");
 #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 (cc_platform_has(CC_ATTR_MEM_ENCRYPT))
+		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);
+
+static void memcpy_fallback(struct iosys_map *dst,
+			    const struct iosys_map *src,
+			    unsigned long len)
+{
+	if (!dst->is_iomem && !src->is_iomem) {
+		memcpy(dst->vaddr, src->vaddr, len);
+	} else if (!src->is_iomem) {
+		iosys_map_memcpy_to(dst, 0, src->vaddr, len);
+	} else if (!dst->is_iomem) {
+		memcpy_fromio(dst->vaddr, src->vaddr_iomem, len);
+	} else {
+		/*
+		 * Bounce size is not performance tuned, but using a
+		 * bounce buffer like this is significantly faster than
+		 * resorting to ioreadxx() + iowritexx().
+		 */
+		char bounce[MEMCPY_BOUNCE_SIZE];
+		void __iomem *_src = src->vaddr_iomem;
+		void __iomem *_dst = dst->vaddr_iomem;
+
+		while (len >= MEMCPY_BOUNCE_SIZE) {
+			memcpy_fromio(bounce, _src, MEMCPY_BOUNCE_SIZE);
+			memcpy_toio(_dst, bounce, MEMCPY_BOUNCE_SIZE);
+			_src += MEMCPY_BOUNCE_SIZE;
+			_dst += MEMCPY_BOUNCE_SIZE;
+			len -= MEMCPY_BOUNCE_SIZE;
+		}
+		if (len) {
+			memcpy_fromio(bounce, _src, MEMCPY_BOUNCE_SIZE);
+			memcpy_toio(_dst, bounce, MEMCPY_BOUNCE_SIZE);
+		}
+	}
+}
+
+#ifdef CONFIG_X86
+
+static DEFINE_STATIC_KEY_FALSE(has_movntdqa);
+
+static void __memcpy_ntdqa(void *dst, const void *src, unsigned long len)
+{
+	kernel_fpu_begin();
+
+	while (len >= 4) {
+		asm("movntdqa	(%0), %%xmm0\n"
+		    "movntdqa 16(%0), %%xmm1\n"
+		    "movntdqa 32(%0), %%xmm2\n"
+		    "movntdqa 48(%0), %%xmm3\n"
+		    "movaps %%xmm0,   (%1)\n"
+		    "movaps %%xmm1, 16(%1)\n"
+		    "movaps %%xmm2, 32(%1)\n"
+		    "movaps %%xmm3, 48(%1)\n"
+		    :: "r" (src), "r" (dst) : "memory");
+		src += 64;
+		dst += 64;
+		len -= 4;
+	}
+	while (len--) {
+		asm("movntdqa (%0), %%xmm0\n"
+		    "movaps %%xmm0, (%1)\n"
+		    :: "r" (src), "r" (dst) : "memory");
+		src += 16;
+		dst += 16;
+	}
+
+	kernel_fpu_end();
+}
+
+/*
+ * __drm_memcpy_from_wc copies @len bytes from @src to @dst using
+ * non-temporal instructions where available. Note that all arguments
+ * (@src, @dst) must be aligned to 16 bytes and @len must be a multiple
+ * of 16.
+ */
+static void __drm_memcpy_from_wc(void *dst, const void *src, unsigned long len)
+{
+	if (unlikely(((unsigned long)dst | (unsigned long)src | len) & 15))
+		memcpy(dst, src, len);
+	else if (likely(len))
+		__memcpy_ntdqa(dst, src, len >> 4);
+}
+
+/**
+ * drm_memcpy_from_wc - Perform the fastest available memcpy from a source
+ * that may be WC.
+ * @dst: The destination pointer
+ * @src: The source pointer
+ * @len: The size of the area o transfer in bytes
+ *
+ * Tries an arch optimized memcpy for prefetching reading out of a WC region,
+ * and if no such beast is available, falls back to a normal memcpy.
+ */
+void drm_memcpy_from_wc(struct iosys_map *dst,
+			const struct iosys_map *src,
+			unsigned long len)
+{
+	if (WARN_ON(in_interrupt())) {
+		memcpy_fallback(dst, src, len);
+		return;
+	}
+
+	if (static_branch_likely(&has_movntdqa)) {
+		__drm_memcpy_from_wc(dst->is_iomem ?
+				     (void __force *)dst->vaddr_iomem :
+				     dst->vaddr,
+				     src->is_iomem ?
+				     (void const __force *)src->vaddr_iomem :
+				     src->vaddr,
+				     len);
+		return;
+	}
+
+	memcpy_fallback(dst, src, len);
+}
+EXPORT_SYMBOL(drm_memcpy_from_wc);
+
+/*
+ * drm_memcpy_init_early - One time initialization of the WC memcpy code
+ */
+void drm_memcpy_init_early(void)
+{
+	/*
+	 * Some hypervisors (e.g. KVM) don't support VEX-prefix instructions
+	 * emulation. So don't enable movntdqa in hypervisor guest.
+	 */
+	if (static_cpu_has(X86_FEATURE_XMM4_1) &&
+	    !boot_cpu_has(X86_FEATURE_HYPERVISOR))
+		static_branch_enable(&has_movntdqa);
+}
+#else
+void drm_memcpy_from_wc(struct iosys_map *dst,
+			const struct iosys_map *src,
+			unsigned long len)
+{
+	WARN_ON(in_interrupt());
+
+	memcpy_fallback(dst, src, len);
+}
+EXPORT_SYMBOL(drm_memcpy_from_wc);
+
+void drm_memcpy_init_early(void)
+{
+}
+#endif /* CONFIG_X86 */