Hi Dexuan,

On Fri, Nov 20, 2020 at 05:45:47PM -0800, Dexuan Cui wrote:

Late in 2019, 2 commits (see the 2 Fixes tags) were introduced to mitigate the slow framebuffer issue. Now that we have fixed the slowness issue by correctly mapping the MMIO VRAM (see commit 5f1251a48c17 ("video: hyperv_fb: Fix the cache type when mapping the VRAM")), we can remove most of the code introduced by the 2 commits, i.e. we no longer need to allocate physical memory and use it to back up the VRAM in Generation-1 VM, and we also no longer need to allocate physical memory to back up the framebuffer in a Generation-2 VM and copy the framebuffer to the real VRAM.

synthvid_deferred_io() is kept, because it's still desirable to send the SYNTHVID_DIRT message only for the exact dirty rectangle, and only when needed.

Fixes: d21987d709e8 ("video: hyperv: hyperv_fb: Support deferred IO for Hyper-V frame buffer driver") Fixes: 3a6fb6c4255c ("video: hyperv: hyperv_fb: Use physical memory for fb on HyperV Gen 1 VMs.") Cc: Wei Hu weh@microsoft.com Cc: Boqun Feng boqun.feng@gmail.com Signed-off-by: Dexuan Cui decui@microsoft.com

After I applied this patch and patch ("video: hyperv_fb: Fix the cache type when mapping the VRAM") on my development branch (with Michael's patchset for ARM64 core support on Hyper-V), and everything worked fine. So feel free to add:

Tested-by: Boqun Feng boqun.feng@gmail.com

Regards, Bqoun

---

This patch changes drivers/video/fbdev/Kconfig, but I hope this can still go through the Hyper-V tree https://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux.git/log/?h=hype... because it's unlikely to cause any build issue to other fbdev drivers (that line was introduced by 3a6fb6c4255c only for hyperv_fb.c)

Note: this patch is based on the Hyper-V tree's hyperv-fixes branch, but it should also apply cleanly to the branch hyperv-next if the commit 5f1251a48c17 is applied first. This patch is for v5.11 rather than v5.10.

drivers/video/fbdev/Kconfig | 1 - drivers/video/fbdev/hyperv_fb.c | 170 ++------------------------------ 2 files changed, 9 insertions(+), 162 deletions(-)

diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig index 402e85450bb5..05b37fb3c6d6 100644 --- a/drivers/video/fbdev/Kconfig +++ b/drivers/video/fbdev/Kconfig @@ -2205,7 +2205,6 @@ config FB_HYPERV select FB_CFB_COPYAREA select FB_CFB_IMAGEBLIT select FB_DEFERRED_IO

• select DMA_CMA if HAVE_DMA_CONTIGUOUS && CMA help This framebuffer driver supports Microsoft Hyper-V Synthetic Video.

diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c index 58c74d2356ba..8131f4e66f98 100644 --- a/drivers/video/fbdev/hyperv_fb.c +++ b/drivers/video/fbdev/hyperv_fb.c @@ -31,16 +31,6 @@

• "set-vmvideo" command. For example

• set-vmvideo -vmname name -horizontalresolution:1920 \
  

• -verticalresolution:1200 -resolutiontype single

• • Gen 1 VMs also support direct using VM's physical memory for framebuffer.
• • It could improve the efficiency and performance for framebuffer and VM.
• • This requires to allocate contiguous physical memory from Linux kernel's
• • CMA memory allocator. To enable this, supply a kernel parameter to give
• • enough memory space to CMA allocator for framebuffer. For example:
• • cma=130m
• • This gives 130MB memory to CMA allocator that can be allocated to
• • framebuffer. For reference, 8K resolution (7680x4320) takes about
• • 127MB memory.
  */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt @@ -267,16 +257,8 @@ struct hvfb_par { /* If true, the VSC notifies the VSP on every framebuffer change */ bool synchronous_fb;

• /* If true, need to copy from deferred IO mem to framebuffer mem */

• bool need_docopy;

• struct notifier_block hvfb_panic_nb;

• /* Memory for deferred IO and frame buffer itself */

• unsigned char *dio_vp;

• unsigned char *mmio_vp;

• phys_addr_t mmio_pp;

• /* Dirty rectangle, protected by delayed_refresh_lock */ int x1, y1, x2, y2; bool delayed_refresh;

@@ -405,21 +387,6 @@ synthvid_update(struct fb_info *info, int x1, int y1, int x2, int y2) return 0; }

-static void hvfb_docopy(struct hvfb_par *par,

• 	unsigned long offset,
  

• 	unsigned long size)
  

-{

• if (!par || !par->mmio_vp || !par->dio_vp || !par->fb_ready ||

•    size == 0 || offset >= dio_fb_size)
  

• return;
  

• if (offset + size > dio_fb_size)

• size = dio_fb_size - offset;
  

• memcpy(par->mmio_vp + offset, par->dio_vp + offset, size);

-}

-/* Deferred IO callback */ static void synthvid_deferred_io(struct fb_info *p, struct list_head *pagelist) { @@ -444,10 +411,6 @@ static void synthvid_deferred_io(struct fb_info *p, y2 = end / p->fix.line_length; miny = min_t(int, miny, y1); maxy = max_t(int, maxy, y2);

• /* Copy from dio space to mmio address */
  

• if (par->fb_ready && par->need_docopy)
  

• 	hvfb_docopy(par, start, PAGE_SIZE);
  

  }

  if (par->fb_ready && par->update)

@@ -704,7 +667,7 @@ static int synthvid_send_config(struct hv_device *hdev) msg->vid_hdr.type = SYNTHVID_VRAM_LOCATION; msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) + sizeof(struct synthvid_vram_location);

• msg->vram.user_ctx = msg->vram.vram_gpa = par->mmio_pp;

• msg->vram.user_ctx = msg->vram.vram_gpa = info->fix.smem_start; msg->vram.is_vram_gpa_specified = 1; synthvid_send(hdev, msg);

@@ -714,7 +677,7 @@ static int synthvid_send_config(struct hv_device *hdev) ret = -ETIMEDOUT; goto out; }

• if (msg->vram_ack.user_ctx != par->mmio_pp) {

• if (msg->vram_ack.user_ctx != info->fix.smem_start) { pr_err("Unable to set VRAM location\n"); ret = -ENODEV; goto out;

@@ -740,7 +703,6 @@ static void hvfb_update_work(struct work_struct *w) struct fb_info *info = par->info; unsigned long flags; int x1, x2, y1, y2;

• int j;

  spin_lock_irqsave(&par->delayed_refresh_lock, flags); /* Reset the request flag */

@@ -762,14 +724,6 @@ static void hvfb_update_work(struct work_struct *w) y1 > info->var.yres || y2 > info->var.yres || x2 <= x1) return;

• /* Copy the dirty rectangle to frame buffer memory */
• if (par->need_docopy)

• for (j = y1; j < y2; j++)
  

• 	hvfb_docopy(par,
  

• 		    j * info->fix.line_length +
  

• 		    (x1 * screen_depth / 8),
  

• 		    (x2 - x1) * screen_depth / 8);
  

• /* Refresh */ if (par->fb_ready && par->update) synthvid_update(info, x1, y1, x2, y2);

@@ -813,8 +767,6 @@ static int hvfb_on_panic(struct notifier_block *nb, par = container_of(nb, struct hvfb_par, hvfb_panic_nb); par->synchronous_fb = true; info = par->info;

• if (par->need_docopy)

• hvfb_docopy(par, 0, dio_fb_size);
  

  synthvid_update(info, 0, 0, INT_MAX, INT_MAX);

  return NOTIFY_DONE;

@@ -953,62 +905,6 @@ static void hvfb_get_option(struct fb_info *info) return; }

-/*

• • Allocate enough contiguous physical memory.
• • Return physical address if succeeded or -1 if failed.
• */

-static phys_addr_t hvfb_get_phymem(struct hv_device *hdev,

• 		   unsigned int request_size)
  

-{

• struct page *page = NULL;
• dma_addr_t dma_handle;
• void *vmem;
• phys_addr_t paddr = 0;
• unsigned int order = get_order(request_size);
• if (request_size == 0)

• return -1;
  

• if (order < MAX_ORDER) {

• /* Call alloc_pages if the size is less than 2^MAX_ORDER */
  

• page = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
  

• if (!page)
  

• 	return -1;
  

• paddr = (page_to_pfn(page) << PAGE_SHIFT);
  

• } else {

• /* Allocate from CMA */
  

• hdev->device.coherent_dma_mask = DMA_BIT_MASK(64);
  

• vmem = dma_alloc_coherent(&hdev->device,
  

• 			  round_up(request_size, PAGE_SIZE),
  

• 			  &dma_handle,
  

• 			  GFP_KERNEL | __GFP_NOWARN);
  

• if (!vmem)
  

• 	return -1;
  

• paddr = virt_to_phys(vmem);
  

• }
• return paddr;

-}

-/* Release contiguous physical memory */ -static void hvfb_release_phymem(struct hv_device *hdev,

• 		phys_addr_t paddr, unsigned int size)
  

-{

• unsigned int order = get_order(size);
• if (order < MAX_ORDER)

• __free_pages(pfn_to_page(paddr >> PAGE_SHIFT), order);
  

• else

• dma_free_coherent(&hdev->device,
  

• 		  round_up(size, PAGE_SIZE),
  

• 		  phys_to_virt(paddr),
  

• 		  paddr);
  

-}

/* Get framebuffer memory from Hyper-V video pci space */ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info) @@ -1018,7 +914,6 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info) void __iomem *fb_virt; int gen2vm = efi_enabled(EFI_BOOT); resource_size_t pot_start, pot_end;

• phys_addr_t paddr; int ret;

  info->apertures = alloc_apertures(1);

@@ -1036,38 +931,12 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info)

info->apertures->ranges[0].base = pci_resource_start(pdev, 0);
info->apertures->ranges[0].size = pci_resource_len(pdev, 0);

• /*
  

•  * For Gen 1 VM, we can directly use the contiguous memory
  

•  * from VM. If we succeed, deferred IO happens directly
  

•  * on this allocated framebuffer memory, avoiding extra
  

•  * memory copy.
  

•  */
  

• paddr = hvfb_get_phymem(hdev, screen_fb_size);
  

• if (paddr != (phys_addr_t) -1) {
  

• 	par->mmio_pp = paddr;
  

• 	par->mmio_vp = par->dio_vp = __va(paddr);
  

• 	info->fix.smem_start = paddr;
  

• 	info->fix.smem_len = screen_fb_size;
  

• 	info->screen_base = par->mmio_vp;
  

• 	info->screen_size = screen_fb_size;
  

• 	par->need_docopy = false;
  

• 	goto getmem_done;
  

• }
  

• pr_info("Unable to allocate enough contiguous physical memory on Gen 1 VM. Using MMIO instead.\n");
  

  } else { info->apertures->ranges[0].base = screen_info.lfb_base; info->apertures->ranges[0].size = screen_info.lfb_size; }

• /*

• * Cannot use the contiguous physical memory.
  

• * Allocate mmio space for framebuffer.
  

• */
  

• dio_fb_size =

• screen_width * screen_height * screen_depth / 8;
  

• dio_fb_size = screen_width * screen_height * screen_depth / 8;

  if (gen2vm) { pot_start = 0;

@@ -1101,22 +970,11 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info) if (!fb_virt) goto err2;

• /* Allocate memory for deferred IO */
• par->dio_vp = vzalloc(round_up(dio_fb_size, PAGE_SIZE));
• if (par->dio_vp == NULL)

• goto err3;
  

• /* Physical address of FB device */
• par->mmio_pp = par->mem->start;
• /* Virtual address of FB device */
• par->mmio_vp = (unsigned char *) fb_virt;
• info->fix.smem_start = par->mem->start; info->fix.smem_len = dio_fb_size;
• info->screen_base = par->dio_vp;

• info->screen_base = fb_virt; info->screen_size = dio_fb_size;

-getmem_done: remove_conflicting_framebuffers(info->apertures, KBUILD_MODNAME, false); if (!gen2vm) @@ -1125,8 +983,6 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info)

return 0;

-err3:

• iounmap(fb_virt);

err2: vmbus_free_mmio(par->mem->start, screen_fb_size); par->mem = NULL; @@ -1139,19 +995,12 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info) }

/* Release the framebuffer */ -static void hvfb_putmem(struct hv_device *hdev, struct fb_info *info) +static void hvfb_putmem(struct fb_info *info) { struct hvfb_par *par = info->par;

• if (par->need_docopy) {

• vfree(par->dio_vp);
  

• iounmap(info->screen_base);
  

• vmbus_free_mmio(par->mem->start, screen_fb_size);
  

• } else {

• hvfb_release_phymem(hdev, info->fix.smem_start,
  

• 		    screen_fb_size);
  

• }

• iounmap(info->screen_base);
• vmbus_free_mmio(par->mem->start, screen_fb_size); par->mem = NULL;

}

@@ -1170,7 +1019,6 @@ static int hvfb_probe(struct hv_device *hdev, par = info->par; par->info = info; par->fb_ready = false;

• par->need_docopy = true; init_completion(&par->wait); INIT_DELAYED_WORK(&par->dwork, hvfb_update_work);

@@ -1256,7 +1104,7 @@ static int hvfb_probe(struct hv_device *hdev,

error: fb_deferred_io_cleanup(info);

• hvfb_putmem(hdev, info);

• hvfb_putmem(info);

error2: vmbus_close(hdev->channel); error1: @@ -1286,7 +1134,7 @@ static int hvfb_remove(struct hv_device *hdev) vmbus_close(hdev->channel); hv_set_drvdata(hdev, NULL);

• hvfb_putmem(hdev, info);

• hvfb_putmem(info); framebuffer_release(info);

  return 0;

-- 2.19.1