On Hyper-V, Generation 1 VMs can directly use VM's physical memory for
their framebuffers. This can improve the efficiency of framebuffer and
overall performence for VM. The physical memory assigned to framebuffer
must be contiguous. We use CMA allocator to get contiguouse physicial
memory when the framebuffer size is greater than 4MB. For size under
4MB, we use alloc_pages to achieve this.
To enable framebuffer memory allocation from CMA, supply a kernel
parameter to give enough space to CMA allocator at boot time. For
example:
cma=130m
This gives 130MB memory to CAM allocator that can be allocated to
framebuffer. If this fails, we fall back to the old way of using
mmio for framebuffer.
Signed-off-by: Wei Hu <[email protected]>
---
v2: Incorporated review comments form [email protected], Michael Kelley and
Dexuan Cui
- Use dma_alloc_coherent to allocate large contiguous memory
- Use phys_addr_t for physical addresses
- Corrected a few spelling errors and minor cleanups
- Also tested on 32 bit Ubuntu guest
drivers/video/fbdev/Kconfig | 1 +
drivers/video/fbdev/hyperv_fb.c | 196 +++++++++++++++++++++++++-------
2 files changed, 158 insertions(+), 39 deletions(-)
diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
index aa9541bf964b..87b82de4598d 100644
--- a/drivers/video/fbdev/Kconfig
+++ b/drivers/video/fbdev/Kconfig
@@ -2215,6 +2215,7 @@ config FB_HYPERV
select FB_CFB_COPYAREA
select FB_CFB_IMAGEBLIT
select FB_DEFERRED_IO
+ select DMA_CMA if HAVE_DMA_CONTIGUOUS
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 3f60b7bc8589..8ba96764c749 100644
--- a/drivers/video/fbdev/hyperv_fb.c
+++ b/drivers/video/fbdev/hyperv_fb.c
@@ -31,6 +31,16 @@
* "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
@@ -227,7 +237,6 @@ struct synthvid_msg {
} __packed;
-
/* FB driver definitions and structures */
#define HVFB_WIDTH 1152 /* default screen width */
#define HVFB_HEIGHT 864 /* default screen height */
@@ -256,12 +265,15 @@ 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;
- unsigned long mmio_pp;
+ phys_addr_t mmio_pp;
/* Dirty rectangle, protected by delayed_refresh_lock */
int x1, y1, x2, y2;
@@ -432,7 +444,7 @@ static void synthvid_deferred_io(struct fb_info *p,
maxy = max_t(int, maxy, y2);
/* Copy from dio space to mmio address */
- if (par->fb_ready)
+ if (par->fb_ready && par->need_docopy)
hvfb_docopy(par, start, PAGE_SIZE);
}
@@ -749,12 +761,12 @@ static void hvfb_update_work(struct work_struct *w)
return;
/* Copy the dirty rectangle to frame buffer memory */
- for (j = y1; j < y2; j++) {
- hvfb_docopy(par,
- j * info->fix.line_length +
- (x1 * screen_depth / 8),
- (x2 - x1) * screen_depth / 8);
- }
+ 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)
@@ -799,7 +811,8 @@ 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;
- hvfb_docopy(par, 0, dio_fb_size);
+ if (par->need_docopy)
+ hvfb_docopy(par, 0, dio_fb_size);
synthvid_update(info, 0, 0, INT_MAX, INT_MAX);
return NOTIFY_DONE;
@@ -938,6 +951,74 @@ 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;
+ unsigned int request_pages;
+ phys_addr_t paddr = 0;
+ unsigned int order = get_order(request_size);
+
+ if (request_size == 0)
+ return -1;
+
+ /* Try to call alloc_pages if the size is less than 2^MAX_ORDER */
+ if (order < MAX_ORDER) {
+ page = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
+ if (!page)
+ return -1;
+
+ paddr = (page_to_pfn(page) << PAGE_SHIFT);
+ request_pages = (1 << order);
+ goto get_phymem1;
+ }
+
+ /* Allocate from CMA */
+ if (hdev == NULL)
+ return -1;
+
+ hdev->device.coherent_dma_mask = DMA_BIT_MASK(64);
+
+ request_pages = (round_up(request_size, PAGE_SIZE) >> PAGE_SHIFT);
+
+ vmem = dma_alloc_coherent(&hdev->device,
+ request_pages * PAGE_SIZE,
+ &dma_handle,
+ GFP_KERNEL | __GFP_NOWARN);
+
+ if (!vmem)
+ return -1;
+
+ paddr = virt_to_phys(vmem);
+
+get_phymem1:
+ pr_info("Allocated %d pages starts at physical addr 0x%llx\n",
+ request_pages, paddr);
+
+ 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)
@@ -947,8 +1028,57 @@ 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;
+ if (!gen2vm) {
+ pdev = pci_get_device(PCI_VENDOR_ID_MICROSOFT,
+ PCI_DEVICE_ID_HYPERV_VIDEO, NULL);
+ if (!pdev) {
+ pr_err("Unable to find PCI Hyper-V video\n");
+ return -ENODEV;
+ }
+ }
+
+ info->apertures = alloc_apertures(1);
+ if (!info->apertures)
+ goto err1;
+
+ if (gen2vm) {
+ info->apertures->ranges[0].base = screen_info.lfb_base;
+ info->apertures->ranges[0].size = screen_info.lfb_size;
+ } else {
+ 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.
+ */
+ if (!gen2vm) {
+ 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 getmem1;
+ }
+ pr_info("Unable to allocate enough contiguous physical memory on Gen 1 VM. Use MMIO instead.\n");
+ }
+
+ /*
+ * Cannot use the contiguous physical memory.
+ * Allocate mmio space for framebuffer.
+ */
dio_fb_size =
screen_width * screen_height * screen_depth / 8;
@@ -956,13 +1086,6 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info)
pot_start = 0;
pot_end = -1;
} else {
- pdev = pci_get_device(PCI_VENDOR_ID_MICROSOFT,
- PCI_DEVICE_ID_HYPERV_VIDEO, NULL);
- if (!pdev) {
- pr_err("Unable to find PCI Hyper-V video\n");
- return -ENODEV;
- }
-
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",
@@ -991,20 +1114,6 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info)
if (par->dio_vp == NULL)
goto err3;
- info->apertures = alloc_apertures(1);
- if (!info->apertures)
- goto err4;
-
- if (gen2vm) {
- info->apertures->ranges[0].base = screen_info.lfb_base;
- info->apertures->ranges[0].size = screen_info.lfb_size;
- remove_conflicting_framebuffers(info->apertures,
- KBUILD_MODNAME, false);
- } else {
- info->apertures->ranges[0].base = pci_resource_start(pdev, 0);
- info->apertures->ranges[0].size = pci_resource_len(pdev, 0);
- }
-
/* Physical address of FB device */
par->mmio_pp = par->mem->start;
/* Virtual address of FB device */
@@ -1015,13 +1124,15 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info)
info->screen_base = par->dio_vp;
info->screen_size = dio_fb_size;
+getmem1:
+ remove_conflicting_framebuffers(info->apertures,
+ KBUILD_MODNAME, false);
+
if (!gen2vm)
pci_dev_put(pdev);
return 0;
-err4:
- vfree(par->dio_vp);
err3:
iounmap(fb_virt);
err2:
@@ -1035,13 +1146,19 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info)
}
/* Release the framebuffer */
-static void hvfb_putmem(struct fb_info *info)
+static void hvfb_putmem(struct hv_device *hdev, struct fb_info *info)
{
struct hvfb_par *par = info->par;
- vfree(par->dio_vp);
- iounmap(info->screen_base);
- vmbus_free_mmio(par->mem->start, screen_fb_size);
+ 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);
+ }
+
par->mem = NULL;
}
@@ -1060,6 +1177,7 @@ 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);
@@ -1145,7 +1263,7 @@ static int hvfb_probe(struct hv_device *hdev,
error:
fb_deferred_io_cleanup(info);
- hvfb_putmem(info);
+ hvfb_putmem(hdev, info);
error2:
vmbus_close(hdev->channel);
error1:
@@ -1175,7 +1293,7 @@ static int hvfb_remove(struct hv_device *hdev)
vmbus_close(hdev->channel);
hv_set_drvdata(hdev, NULL);
- hvfb_putmem(info);
+ hvfb_putmem(hdev, info);
framebuffer_release(info);
return 0;
--
2.20.1
Hi Wei,
I love your patch! Perhaps something to improve:
[auto build test WARNING on next-20191122]
[cannot apply to linus/master v5.4-rc8 v5.4-rc7 v5.4-rc6 v5.4]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
url: https://github.com/0day-ci/linux/commits/Wei-Hu/video-hyperv-hyperv_fb-Use-physical-memory-for-fb-on-HyperV-Gen-1-VMs/20191124-163533
base: b9d3d01405061bb42358fe53f824e894a1922ced
config: i386-allmodconfig (attached as .config)
compiler: gcc-7 (Debian 7.4.0-14) 7.4.0
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <[email protected]>
All warnings (new ones prefixed by >>):
In file included from include/linux/printk.h:7:0,
from include/linux/kernel.h:15,
from include/linux/list.h:9,
from include/linux/module.h:12,
from drivers/video/fbdev/hyperv_fb.c:48:
drivers/video/fbdev/hyperv_fb.c: In function 'hvfb_get_phymem':
include/linux/kern_levels.h:5:18: warning: format '%llx' expects argument of type 'long long unsigned int', but argument 3 has type 'phys_addr_t {aka unsigned int}' [-Wformat=]
#define KERN_SOH "\001" /* ASCII Start Of Header */
^
include/linux/kern_levels.h:14:19: note: in expansion of macro 'KERN_SOH'
#define KERN_INFO KERN_SOH "6" /* informational */
^~~~~~~~
include/linux/printk.h:311:9: note: in expansion of macro 'KERN_INFO'
printk(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
^~~~~~~~~
>> drivers/video/fbdev/hyperv_fb.c:1003:2: note: in expansion of macro 'pr_info'
pr_info("Allocated %d pages starts at physical addr 0x%llx\n",
^~~~~~~
vim +/pr_info +1003 drivers/video/fbdev/hyperv_fb.c
955
956 /*
957 * Allocate enough contiguous physical memory.
958 * Return physical address if succeeded or -1 if failed.
959 */
960 static phys_addr_t hvfb_get_phymem(struct hv_device *hdev,
961 unsigned int request_size)
962 {
963 struct page *page = NULL;
964 dma_addr_t dma_handle;
965 void *vmem;
966 unsigned int request_pages;
967 phys_addr_t paddr = 0;
968 unsigned int order = get_order(request_size);
969
970 if (request_size == 0)
971 return -1;
972
973 /* Try to call alloc_pages if the size is less than 2^MAX_ORDER */
974 if (order < MAX_ORDER) {
975 page = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
976 if (!page)
977 return -1;
978
979 paddr = (page_to_pfn(page) << PAGE_SHIFT);
980 request_pages = (1 << order);
981 goto get_phymem1;
982 }
983
984 /* Allocate from CMA */
985 if (hdev == NULL)
986 return -1;
987
988 hdev->device.coherent_dma_mask = DMA_BIT_MASK(64);
989
990 request_pages = (round_up(request_size, PAGE_SIZE) >> PAGE_SHIFT);
991
992 vmem = dma_alloc_coherent(&hdev->device,
993 request_pages * PAGE_SIZE,
994 &dma_handle,
995 GFP_KERNEL | __GFP_NOWARN);
996
997 if (!vmem)
998 return -1;
999
1000 paddr = virt_to_phys(vmem);
1001
1002 get_phymem1:
> 1003 pr_info("Allocated %d pages starts at physical addr 0x%llx\n",
1004 request_pages, paddr);
1005
1006 return paddr;
1007 }
1008
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/hyperkitty/list/[email protected] Intel Corporation
Hi Wei,
I love your patch! Yet something to improve:
[auto build test ERROR on next-20191122]
[cannot apply to linus/master v5.4-rc8 v5.4-rc7 v5.4-rc6 v5.4]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
url: https://github.com/0day-ci/linux/commits/Wei-Hu/video-hyperv-hyperv_fb-Use-physical-memory-for-fb-on-HyperV-Gen-1-VMs/20191124-163533
base: b9d3d01405061bb42358fe53f824e894a1922ced
config: i386-randconfig-b003-20191125 (attached as .config)
compiler: gcc-7 (Debian 7.4.0-14) 7.4.0
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <[email protected]>
All errors (new ones prefixed by >>):
ld: kernel/dma/contiguous.o: in function `dma_alloc_from_contiguous':
>> kernel/dma/contiguous.c:199: undefined reference to `cma_alloc'
>> ld: kernel/dma/contiguous.c:199: undefined reference to `cma_alloc'
ld: kernel/dma/contiguous.o: in function `dma_release_from_contiguous':
>> kernel/dma/contiguous.c:215: undefined reference to `cma_release'
>> ld: kernel/dma/contiguous.c:215: undefined reference to `cma_release'
ld: kernel/dma/contiguous.o: in function `dma_alloc_contiguous':
kernel/dma/contiguous.c:248: undefined reference to `cma_alloc'
ld: kernel/dma/contiguous.o: in function `dma_free_contiguous':
kernel/dma/contiguous.c:267: undefined reference to `cma_release'
ld: kernel/dma/contiguous.c:267: undefined reference to `cma_release'
ld: kernel/dma/contiguous.o: in function `dma_contiguous_reserve_area':
>> kernel/dma/contiguous.c:169: undefined reference to `cma_declare_contiguous'
>> ld: kernel/dma/contiguous.c:175: undefined reference to `cma_get_size'
>> ld: kernel/dma/contiguous.c:175: undefined reference to `cma_get_base'
vim +199 kernel/dma/contiguous.c
c64be2bb1c6eb4 drivers/base/dma-contiguous.c Marek Szyprowski 2011-12-29 145
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 146 /**
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 147 * dma_contiguous_reserve_area() - reserve custom contiguous area
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 148 * @size: Size of the reserved area (in bytes),
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 149 * @base: Base address of the reserved area optional, use 0 for any
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 150 * @limit: End address of the reserved memory (optional, 0 for any).
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 151 * @res_cma: Pointer to store the created cma region.
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 152 * @fixed: hint about where to place the reserved area
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 153 *
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 154 * This function reserves memory from early allocator. It should be
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 155 * called by arch specific code once the early allocator (memblock or bootmem)
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 156 * has been activated and all other subsystems have already allocated/reserved
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 157 * memory. This function allows to create custom reserved areas for specific
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 158 * devices.
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 159 *
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 160 * If @fixed is true, reserve contiguous area at exactly @base. If false,
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 161 * reserve in range from @base to @limit.
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 162 */
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 163 int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 164 phys_addr_t limit, struct cma **res_cma,
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 165 bool fixed)
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 166 {
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 167 int ret;
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 168
f318dd083c8128 drivers/base/dma-contiguous.c Laura Abbott 2017-04-18 @169 ret = cma_declare_contiguous(base, size, limit, 0, 0, fixed,
f318dd083c8128 drivers/base/dma-contiguous.c Laura Abbott 2017-04-18 170 "reserved", res_cma);
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 171 if (ret)
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 172 return ret;
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 173
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 174 /* Architecture specific contiguous memory fixup. */
a254129e8686bf drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 @175 dma_contiguous_early_fixup(cma_get_base(*res_cma),
a254129e8686bf drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 176 cma_get_size(*res_cma));
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 177
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 178 return 0;
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 179 }
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 180
c64be2bb1c6eb4 drivers/base/dma-contiguous.c Marek Szyprowski 2011-12-29 181 /**
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 182 * dma_alloc_from_contiguous() - allocate pages from contiguous area
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 183 * @dev: Pointer to device for which the allocation is performed.
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 184 * @count: Requested number of pages.
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 185 * @align: Requested alignment of pages (in PAGE_SIZE order).
d834c5ab83febf kernel/dma/contiguous.c Marek Szyprowski 2018-08-17 186 * @no_warn: Avoid printing message about failed allocation.
c64be2bb1c6eb4 drivers/base/dma-contiguous.c Marek Szyprowski 2011-12-29 187 *
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 188 * This function allocates memory buffer for specified device. It uses
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 189 * device specific contiguous memory area if available or the default
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 190 * global one. Requires architecture specific dev_get_cma_area() helper
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 191 * function.
c64be2bb1c6eb4 drivers/base/dma-contiguous.c Marek Szyprowski 2011-12-29 192 */
67a2e213e7e937 drivers/base/dma-contiguous.c Rohit Vaswani 2015-10-22 193 struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
d834c5ab83febf kernel/dma/contiguous.c Marek Szyprowski 2018-08-17 194 unsigned int align, bool no_warn)
c64be2bb1c6eb4 drivers/base/dma-contiguous.c Marek Szyprowski 2011-12-29 195 {
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 196 if (align > CONFIG_CMA_ALIGNMENT)
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 197 align = CONFIG_CMA_ALIGNMENT;
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 198
d834c5ab83febf kernel/dma/contiguous.c Marek Szyprowski 2018-08-17 @199 return cma_alloc(dev_get_cma_area(dev), count, align, no_warn);
c64be2bb1c6eb4 drivers/base/dma-contiguous.c Marek Szyprowski 2011-12-29 200 }
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 201
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 202 /**
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 203 * dma_release_from_contiguous() - release allocated pages
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 204 * @dev: Pointer to device for which the pages were allocated.
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 205 * @pages: Allocated pages.
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 206 * @count: Number of allocated pages.
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 207 *
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 208 * This function releases memory allocated by dma_alloc_from_contiguous().
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 209 * It returns false when provided pages do not belong to contiguous area and
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 210 * true otherwise.
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 211 */
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 212 bool dma_release_from_contiguous(struct device *dev, struct page *pages,
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 213 int count)
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 214 {
a254129e8686bf drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 @215 return cma_release(dev_get_cma_area(dev), pages, count);
3162bbd7e65b9c drivers/base/dma-contiguous.c Joonsoo Kim 2014-08-06 216 }
de9e14eebf33a6 drivers/base/dma-contiguous.c Marek Szyprowski 2014-10-13 217
:::::: The code at line 199 was first introduced by commit
:::::: d834c5ab83febf9624ad3b16c3c348aa1e02014c kernel/dma: remove unsupported gfp_mask parameter from dma_alloc_from_contiguous()
:::::: TO: Marek Szyprowski <[email protected]>
:::::: CC: Linus Torvalds <[email protected]>
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/hyperkitty/list/[email protected] Intel Corporation
From: Wei Hu <[email protected]> Sent: Friday, November 22, 2019 12:24 AM
>
> On Hyper-V, Generation 1 VMs can directly use VM's physical memory for
> their framebuffers. This can improve the efficiency of framebuffer and
> overall performence for VM. The physical memory assigned to framebuffer
> must be contiguous. We use CMA allocator to get contiguouse physicial
> memory when the framebuffer size is greater than 4MB. For size under
> 4MB, we use alloc_pages to achieve this.
>
> To enable framebuffer memory allocation from CMA, supply a kernel
> parameter to give enough space to CMA allocator at boot time. For
> example:
> cma=130m
> This gives 130MB memory to CAM allocator that can be allocated to
> framebuffer. If this fails, we fall back to the old way of using
> mmio for framebuffer.
>
> Signed-off-by: Wei Hu <[email protected]>
> ---
> v2: Incorporated review comments form [email protected], Michael Kelley and
> Dexuan Cui
> - Use dma_alloc_coherent to allocate large contiguous memory
> - Use phys_addr_t for physical addresses
> - Corrected a few spelling errors and minor cleanups
> - Also tested on 32 bit Ubuntu guest
>
> drivers/video/fbdev/Kconfig | 1 +
> drivers/video/fbdev/hyperv_fb.c | 196 +++++++++++++++++++++++++-------
> 2 files changed, 158 insertions(+), 39 deletions(-)
>
[snip]
> +/*
> + * 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;
> + unsigned int request_pages;
> + phys_addr_t paddr = 0;
> + unsigned int order = get_order(request_size);
> +
> + if (request_size == 0)
> + return -1;
> +
> + /* Try to call alloc_pages if the size is less than 2^MAX_ORDER */
> + if (order < MAX_ORDER) {
> + page = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
> + if (!page)
> + return -1;
> +
> + paddr = (page_to_pfn(page) << PAGE_SHIFT);
> + request_pages = (1 << order);
> + goto get_phymem1;
> + }
Could you use an 'else' clause here and eliminate the above
'goto' statement? I know that makes the below code be indented
one level deeper, but that doesn't seem particularly problematic
here. The reason we have 'else' clauses is to avoid 'goto's and
labels. :-)
> +
> + /* Allocate from CMA */
> + if (hdev == NULL)
> + return -1;
The above test seems unnecessary. A lot of things would have
broken before getting to this function if hdev was NULL.
> +
> + hdev->device.coherent_dma_mask = DMA_BIT_MASK(64);
> +
> + request_pages = (round_up(request_size, PAGE_SIZE) >> PAGE_SHIFT);
> +
> + vmem = dma_alloc_coherent(&hdev->device,
> + request_pages * PAGE_SIZE,
> + &dma_handle,
> + GFP_KERNEL | __GFP_NOWARN);
> +
> + if (!vmem)
> + return -1;
> +
> + paddr = virt_to_phys(vmem);
> +
> +get_phymem1:
> + pr_info("Allocated %d pages starts at physical addr 0x%llx\n",
> + request_pages, paddr);
I wonder if we want to show the physical address here. The Linux kernel
definitely does not show kernel virtual addresses due to security
concerns, and I'm wondering if the same applies to physical addresses.
What's the benefit to showing the physical address?
And in the message "starts" should be "starting".
> +
> + 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)
> @@ -947,8 +1028,57 @@ 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;
>
> + if (!gen2vm) {
> + pdev = pci_get_device(PCI_VENDOR_ID_MICROSOFT,
> + PCI_DEVICE_ID_HYPERV_VIDEO, NULL);
> + if (!pdev) {
> + pr_err("Unable to find PCI Hyper-V video\n");
> + return -ENODEV;
> + }
> + }
> +
> + info->apertures = alloc_apertures(1);
> + if (!info->apertures)
> + goto err1;
There's a small memory leak here. The apertures are never freed in any
of the error cases in this function, or in hvfb_putmem(). This is not a bug you
introduced -- the original code had the same leak.
> +
> + if (gen2vm) {
> + info->apertures->ranges[0].base = screen_info.lfb_base;
> + info->apertures->ranges[0].size = screen_info.lfb_size;
> + } else {
> + 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.
> + */
> + if (!gen2vm) {
> + 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 getmem1;
Maybe change the 'getmem1' label to 'done' or something similarly
indicative having successfully completed everything that needs to be
done?
> + }
> + pr_info("Unable to allocate enough contiguous physical memory on Gen 1
> VM. Use MMIO instead.\n");
I'd suggest changing the message to say "Using MMIO instead". This is just an
informative message indicating what the driver is doing. "Use MMIO instead"
sounds like a directive to the user to do something different, like change his
kernel configuration, and that's not the intent.
> + }
In the above code, there are three, almost consecutive, tests of the "gen2vm"
variable. It seems like the apertures could be allocated first, and then the three
tests combined into one test. Then you have one range of code for Gen 1 and
another range for Gen 2 and fewer lines 'if' statements, 'else' statements, and
curly braces.
> +
> + /*
> + * Cannot use the contiguous physical memory.
> + * Allocate mmio space for framebuffer.
> + */
> dio_fb_size =
> screen_width * screen_height * screen_depth / 8;
>
> @@ -956,13 +1086,6 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info
> *info)
> pot_start = 0;
> pot_end = -1;
> } else {
> - pdev = pci_get_device(PCI_VENDOR_ID_MICROSOFT,
> - PCI_DEVICE_ID_HYPERV_VIDEO, NULL);
> - if (!pdev) {
> - pr_err("Unable to find PCI Hyper-V video\n");
> - return -ENODEV;
> - }
> -
> 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",
> @@ -991,20 +1114,6 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info
> *info)
> if (par->dio_vp == NULL)
> goto err3;
>
> - info->apertures = alloc_apertures(1);
> - if (!info->apertures)
> - goto err4;
> -
> - if (gen2vm) {
> - info->apertures->ranges[0].base = screen_info.lfb_base;
> - info->apertures->ranges[0].size = screen_info.lfb_size;
> - remove_conflicting_framebuffers(info->apertures,
> - KBUILD_MODNAME, false);
> - } else {
> - info->apertures->ranges[0].base = pci_resource_start(pdev, 0);
> - info->apertures->ranges[0].size = pci_resource_len(pdev, 0);
> - }
> -
> /* Physical address of FB device */
> par->mmio_pp = par->mem->start;
> /* Virtual address of FB device */
> @@ -1015,13 +1124,15 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info
> *info)
> info->screen_base = par->dio_vp;
> info->screen_size = dio_fb_size;
>
> +getmem1:
> + remove_conflicting_framebuffers(info->apertures,
> + KBUILD_MODNAME, false);
With your change, remove_conflicting_framebuffers() is called for both
Gen 1 and Gen 2 VMs. In the old code, it was called only for Gen 2 VMs.
Is this change intentional? If so, why? I haven't delved into the details
of what remove_conflicting_framebuffers() does, so my question is
more of a double-check rather than my definitely thinking something
is wrong.
> +
> if (!gen2vm)
> pci_dev_put(pdev);
>
> return 0;
>
> -err4:
> - vfree(par->dio_vp);
> err3:
> iounmap(fb_virt);
> err2:
> @@ -1035,13 +1146,19 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info
> *info)
> }
>
> /* Release the framebuffer */
> -static void hvfb_putmem(struct fb_info *info)
> +static void hvfb_putmem(struct hv_device *hdev, struct fb_info *info)
> {
> struct hvfb_par *par = info->par;
>
> - vfree(par->dio_vp);
> - iounmap(info->screen_base);
> - vmbus_free_mmio(par->mem->start, screen_fb_size);
> + 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);
> + }
> +
> par->mem = NULL;
There's a small memory leak in the above statement. The data
structure pointed to by "mem" is not freed. The same problem
occurs in hvfb_getmem() in the "err2" path. This bug existed in
the old code as well, so it was not introduced by your changes.
Michael