This patch fixes a bug where GEN1 VMs doesn't allow resolutions greater than 64 MB size (eg 7680x4320). Unnecessary PCI check limits Gen1 VRAM to legacy PCI BAR size only (ie 64MB). Thus any, resolution requesting greater then 64MB (eg 7680x4320) would fail. MMIO region assigning this memory shouldn't be limited by PCI bar size.
Signed-off-by: Saurabh Sengar ssengar@linux.microsoft.com --- drivers/video/fbdev/hyperv_fb.c | 19 +------------------ 1 file changed, 1 insertion(+), 18 deletions(-)
diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c index c8e0ea2..58c304a 100644 --- a/drivers/video/fbdev/hyperv_fb.c +++ b/drivers/video/fbdev/hyperv_fb.c @@ -1009,7 +1009,6 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info) struct pci_dev *pdev = NULL; void __iomem *fb_virt; int gen2vm = efi_enabled(EFI_BOOT); - resource_size_t pot_start, pot_end; phys_addr_t paddr; int ret;
@@ -1060,23 +1059,7 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info) dio_fb_size = screen_width * screen_height * screen_depth / 8;
- if (gen2vm) { - pot_start = 0; - pot_end = -1; - } else { - if (!(pci_resource_flags(pdev, 0) & IORESOURCE_MEM) || - pci_resource_len(pdev, 0) < screen_fb_size) { - pr_err("Resource not available or (0x%lx < 0x%lx)\n", - (unsigned long) pci_resource_len(pdev, 0), - (unsigned long) screen_fb_size); - goto err1; - } - - pot_end = pci_resource_end(pdev, 0); - pot_start = pot_end - screen_fb_size + 1; - } - - ret = vmbus_allocate_mmio(&par->mem, hdev, pot_start, pot_end, + ret = vmbus_allocate_mmio(&par->mem, hdev, 0, -1, screen_fb_size, 0x100000, true); if (ret != 0) { pr_err("Unable to allocate framebuffer memory\n");
On 4/27/22 15:47, Saurabh Sengar wrote:
This patch fixes a bug where GEN1 VMs doesn't allow resolutions greater than 64 MB size (eg 7680x4320). Unnecessary PCI check limits Gen1 VRAM to legacy PCI BAR size only (ie 64MB). Thus any, resolution requesting greater then 64MB (eg 7680x4320) would fail. MMIO region assigning this memory shouldn't be limited by PCI bar size.
Is that right? Allocating more memory than what the PCI bar states? That sounds to me that theoretically the "now bigger" memory framebuffer could overwrite other memory areas or mapped PCI bars. I'd like to see some other person from Microsoft to please comment/ack/nack.
Helge
Signed-off-by: Saurabh Sengar ssengar@linux.microsoft.com
drivers/video/fbdev/hyperv_fb.c | 19 +------------------ 1 file changed, 1 insertion(+), 18 deletions(-)
diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c index c8e0ea2..58c304a 100644 --- a/drivers/video/fbdev/hyperv_fb.c +++ b/drivers/video/fbdev/hyperv_fb.c @@ -1009,7 +1009,6 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info) struct pci_dev *pdev = NULL; void __iomem *fb_virt; int gen2vm = efi_enabled(EFI_BOOT);
- resource_size_t pot_start, pot_end; phys_addr_t paddr; int ret;
@@ -1060,23 +1059,7 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info) dio_fb_size = screen_width * screen_height * screen_depth / 8;
- if (gen2vm) {
pot_start = 0;pot_end = -1;- } else {
if (!(pci_resource_flags(pdev, 0) & IORESOURCE_MEM) ||pci_resource_len(pdev, 0) < screen_fb_size) {pr_err("Resource not available or (0x%lx < 0x%lx)\n",(unsigned long) pci_resource_len(pdev, 0),(unsigned long) screen_fb_size);goto err1;}pot_end = pci_resource_end(pdev, 0);pot_start = pot_end - screen_fb_size + 1;- }
- ret = vmbus_allocate_mmio(&par->mem, hdev, pot_start, pot_end,
- ret = vmbus_allocate_mmio(&par->mem, hdev, 0, -1, screen_fb_size, 0x100000, true); if (ret != 0) { pr_err("Unable to allocate framebuffer memory\n");
On Wed, Apr 27, 2022 at 06:47:53AM -0700, Saurabh Sengar wrote:
This patch fixes a bug where GEN1 VMs doesn't allow resolutions greater than 64 MB size (eg 7680x4320). Unnecessary PCI check limits Gen1 VRAM to legacy PCI BAR size only (ie 64MB). Thus any, resolution requesting greater then 64MB (eg 7680x4320) would fail. MMIO region assigning this memory shouldn't be limited by PCI bar size.
Signed-off-by: Saurabh Sengar ssengar@linux.microsoft.com
drivers/video/fbdev/hyperv_fb.c | 19 +------------------ 1 file changed, 1 insertion(+), 18 deletions(-)
diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c index c8e0ea2..58c304a 100644 --- a/drivers/video/fbdev/hyperv_fb.c +++ b/drivers/video/fbdev/hyperv_fb.c @@ -1009,7 +1009,6 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info) struct pci_dev *pdev = NULL; void __iomem *fb_virt; int gen2vm = efi_enabled(EFI_BOOT);
- resource_size_t pot_start, pot_end; phys_addr_t paddr; int ret;
@@ -1060,23 +1059,7 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info) dio_fb_size = screen_width * screen_height * screen_depth / 8;
- if (gen2vm) {
pot_start = 0;pot_end = -1;- } else {
if (!(pci_resource_flags(pdev, 0) & IORESOURCE_MEM) ||pci_resource_len(pdev, 0) < screen_fb_size) {pr_err("Resource not available or (0x%lx < 0x%lx)\n",(unsigned long) pci_resource_len(pdev, 0),(unsigned long) screen_fb_size);goto err1;
This restriction has been in place since day 1. Haiyang, you wrote this driver. Can you comment on whether this change here is sensible?
Thanks, Wei.
}pot_end = pci_resource_end(pdev, 0);pot_start = pot_end - screen_fb_size + 1;- }
- ret = vmbus_allocate_mmio(&par->mem, hdev, pot_start, pot_end,
- ret = vmbus_allocate_mmio(&par->mem, hdev, 0, -1, screen_fb_size, 0x100000, true); if (ret != 0) { pr_err("Unable to allocate framebuffer memory\n");
-- 1.8.3.1
-----Original Message----- From: Wei Liu wei.liu@kernel.org Sent: Thursday, April 28, 2022 10:38 AM To: Saurabh Sengar ssengar@linux.microsoft.com Cc: Saurabh Singh Sengar ssengar@microsoft.com; KY Srinivasan kys@microsoft.com; Haiyang Zhang haiyangz@microsoft.com; Stephen Hemminger sthemmin@microsoft.com; wei.liu@kernel.org; Dexuan Cui decui@microsoft.com; deller@gmx.de; linux-hyperv@vger.kernel.org; linux- fbdev@vger.kernel.org; dri-devel@lists.freedesktop.org; linux- kernel@vger.kernel.org Subject: Re: [PATCH] video: hyperv_fb: Allow resolutions with size > 64 MB for Gen1
On Wed, Apr 27, 2022 at 06:47:53AM -0700, Saurabh Sengar wrote:
This patch fixes a bug where GEN1 VMs doesn't allow resolutions greater than 64 MB size (eg 7680x4320). Unnecessary PCI check limits Gen1 VRAM to legacy PCI BAR size only (ie 64MB). Thus any, resolution requesting greater then 64MB (eg 7680x4320) would fail. MMIO region assigning this memory shouldn't be limited by PCI bar size.
Signed-off-by: Saurabh Sengar ssengar@linux.microsoft.com
drivers/video/fbdev/hyperv_fb.c | 19 +------------------ 1 file changed, 1 insertion(+), 18 deletions(-)
diff --git a/drivers/video/fbdev/hyperv_fb.c
b/drivers/video/fbdev/hyperv_fb.c
index c8e0ea2..58c304a 100644 --- a/drivers/video/fbdev/hyperv_fb.c +++ b/drivers/video/fbdev/hyperv_fb.c @@ -1009,7 +1009,6 @@ static int hvfb_getmem(struct hv_device *hdev,
struct fb_info *info)
struct pci_dev *pdev = NULL; void __iomem *fb_virt; int gen2vm = efi_enabled(EFI_BOOT);
- resource_size_t pot_start, pot_end; phys_addr_t paddr; int ret;
@@ -1060,23 +1059,7 @@ static int hvfb_getmem(struct hv_device *hdev,
struct fb_info *info)
dio_fb_size = screen_width * screen_height * screen_depth / 8;
- if (gen2vm) {
pot_start = 0;pot_end = -1;- } else {
if (!(pci_resource_flags(pdev, 0) & IORESOURCE_MEM) ||pci_resource_len(pdev, 0) < screen_fb_size) {pr_err("Resource not available or (0x%lx < 0x%lx)\n",(unsigned long) pci_resource_len(pdev, 0),(unsigned long) screen_fb_size);goto err1;This restriction has been in place since day 1. Haiyang, you wrote this driver. Can you comment on whether this change here is sensible?
When I initially implemented this driver 10 years ago, I believe there was smaller limit for the fb... But I think this patch is good for the newer MMIO alloc scheme. I hope to see reviews also from @Dexuan Cui @Michael Kelley (LINUX) who are more familiar with the PCI/BAR/MMIO area.
Thanks, - Haiyang
From: Haiyang Zhang haiyangz@microsoft.com
...
- if (gen2vm) {
pot_start = 0;pot_end = -1;- } else {
if (!(pci_resource_flags(pdev, 0) & IORESOURCE_MEM) ||pci_resource_len(pdev, 0) < screen_fb_size) {pr_err("Resource not available or (0x%lx < 0x%lx)\n",(unsigned long) pci_resource_len(pdev, 0),(unsigned long) screen_fb_size);goto err1;This restriction has been in place since day 1. Haiyang, you wrote this driver. Can you comment on whether this change here is sensible?
When I initially implemented this driver 10 years ago, I believe there was smaller limit for the fb... But I think this patch is good for the newer MMIO alloc scheme. I hope to see reviews also from @Dexuan Cui @Michael Kelley (LINUX) who are more familiar with the PCI/BAR/MMIO area.
Thanks,
- Haiyang
The patch looks good to me but I suggest we check with the Hyper-V team to figure out how a Gen1 Windows VM supports a higher resolution that needs a VRAM size of more than 64MB. Just in case we miss something..
Thanks, -- Dexuan
From: Dexuan Cui decui@microsoft.com Sent: Wednesday, May 4, 2022 10:05 AM To: Haiyang Zhang haiyangz@microsoft.com; Wei Liu wei.liu@kernel.org;
... When I initially implemented this driver 10 years ago, I believe there was smaller limit for the fb... But I think this patch is good for the newer MMIO alloc scheme. I hope to see reviews also from @Dexuan Cui @Michael Kelley (LINUX) who are more familiar with the PCI/BAR/MMIO area.
Thanks,
- Haiyang
The patch looks good to me but I suggest we check with the Hyper-V team to figure out how a Gen1 Windows VM supports a higher resolution that needs a VRAM size of more than 64MB. Just in case we miss something..
Thanks, -- Dexuan
Reviewed-by: Dexuan Cui decui@microsoft.com
Saurabh checked this with Hyper-V team, who said there is no Generation 1-specific block for larger VRAM sizes in Windows VM.
When the driver was originally developed, we didn't have the API vmbus_allocate_mmio(), and I guess we just used the PCI device's BAR address for simplicity, and didn't realize the restriction with very high resolutions that require >64 MB VRAM. It looks like the synthetic VMBus framebuffer device doesn't have to use the same MMIO range used by the Hyper-V legacy PCI framebuffer device, so the patch looks good to me.
BTW, please check the hyperv-drm driver as well: drivers/gpu/drm/hyperv/hyperv_drm_drv.c I think we should make the same change there to support 7680x4320 for Gen1 VMs.
Thanks, Dexuan
On 5/18/22 20:48, Dexuan Cui wrote:
From: Dexuan Cui decui@microsoft.com Sent: Wednesday, May 4, 2022 10:05 AM To: Haiyang Zhang haiyangz@microsoft.com; Wei Liu wei.liu@kernel.org;
... When I initially implemented this driver 10 years ago, I believe there was smaller limit for the fb... But I think this patch is good for the newer MMIO alloc scheme. I hope to see reviews also from @Dexuan Cui @Michael Kelley (LINUX) who are more familiar with the PCI/BAR/MMIO area.
Thanks,
- Haiyang
The patch looks good to me but I suggest we check with the Hyper-V team to figure out how a Gen1 Windows VM supports a higher resolution that needs a VRAM size of more than 64MB. Just in case we miss something..
Thanks, -- Dexuan
Reviewed-by: Dexuan Cui decui@microsoft.com
Saurabh checked this with Hyper-V team, who said there is no Generation 1-specific block for larger VRAM sizes in Windows VM.
When the driver was originally developed, we didn't have the API vmbus_allocate_mmio(), and I guess we just used the PCI device's BAR address for simplicity, and didn't realize the restriction with very high resolutions that require >64 MB VRAM. It looks like the synthetic VMBus framebuffer device doesn't have to use the same MMIO range used by the Hyper-V legacy PCI framebuffer device, so the patch looks good to me.
Thanks for the review, Dexuan!
I've applied this patch now to the fbdev git tree.
BTW, please check the hyperv-drm driver as well: drivers/gpu/drm/hyperv/hyperv_drm_drv.c I think we should make the same change there to support 7680x4320 for Gen1 VMs.
Haiyang, can you check that as well and send another patch for the drm tree ?
Helge
dri-devel@lists.freedesktop.org
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Dexuan Cui -
Haiyang Zhang -
Helge Deller -
Saurabh Sengar -
Wei Liu