hyperv-fb: add support for generation 2 virtual machines.

UEFI-based generation 2 virtual machines support vmbus devices only.
There is no pci bus.  Thus they use a different mechanism for the
graphics framebuffer:  Instead of using the vga pci bar a chunk of
memory muct be allocated from the hyperv mmio region declared using
APCI.  This patch implements support for it.

Based on a patch by Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Acked-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/video/hyperv_fb.c

@@ -42,6 +42,7 @@
 #include <linux/completion.h>
 #include <linux/fb.h>
 #include <linux/pci.h>
+#include <linux/efi.h>
 
 #include <linux/hyperv.h>
 
@@ -212,6 +213,7 @@ struct synthvid_msg {
 
 struct hvfb_par {
 	struct fb_info *info;
+	struct resource mem;
 	bool fb_ready; /* fb device is ready */
 	struct completion wait;
 	u32 synthvid_version;
@@ -460,13 +462,13 @@ static int synthvid_connect_vsp(struct hv_device *hdev)
 		goto error;
 	}
 
-	if (par->synthvid_version == SYNTHVID_VERSION_WIN7) {
+	if (par->synthvid_version == SYNTHVID_VERSION_WIN7)
 		screen_depth = SYNTHVID_DEPTH_WIN7;
-		screen_fb_size = SYNTHVID_FB_SIZE_WIN7;
-	} else {
+	else
 		screen_depth = SYNTHVID_DEPTH_WIN8;
-		screen_fb_size = SYNTHVID_FB_SIZE_WIN8;
-	}
+
+	screen_fb_size = hdev->channel->offermsg.offer.
+				mmio_megabytes * 1024 * 1024;
 
 	return 0;
 
@@ -627,26 +629,46 @@ static void hvfb_get_option(struct fb_info *info)
 /* Get framebuffer memory from Hyper-V video pci space */
 static int hvfb_getmem(struct fb_info *info)
 {
-	struct pci_dev *pdev;
-	ulong fb_phys;
+	struct hvfb_par *par = info->par;
+	struct pci_dev *pdev  = NULL;
 	void __iomem *fb_virt;
+	int gen2vm = efi_enabled(EFI_BOOT);
+	int ret;
 
-	pdev = pci_get_device(PCI_VENDOR_ID_MICROSOFT,
+	par->mem.name = KBUILD_MODNAME;
+	par->mem.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+	if (gen2vm) {
+		ret = allocate_resource(&hyperv_mmio, &par->mem,
+					screen_fb_size,
+					0, -1,
+					screen_fb_size,
+					NULL, NULL);
+		if (ret != 0) {
+			pr_err("Unable to allocate framebuffer memory\n");
+			return -ENODEV;
+		}
+	} 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 (!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)
-		goto err1;
+		if (!(pci_resource_flags(pdev, 0) & IORESOURCE_MEM) ||
+		    pci_resource_len(pdev, 0) < screen_fb_size)
+			goto err1;
 
-	fb_phys = pci_resource_end(pdev, 0) - screen_fb_size + 1;
-	if (!request_mem_region(fb_phys, screen_fb_size, KBUILD_MODNAME))
-		goto err1;
+		par->mem.end = pci_resource_end(pdev, 0);
+		par->mem.start = par->mem.end - screen_fb_size + 1;
+		ret = request_resource(&pdev->resource[0], &par->mem);
+		if (ret != 0) {
+			pr_err("Unable to request framebuffer memory\n");
+			goto err1;
+		}
+	}
 
-	fb_virt = ioremap(fb_phys, screen_fb_size);
+	fb_virt = ioremap(par->mem.start, screen_fb_size);
 	if (!fb_virt)
 		goto err2;
 
@@ -654,30 +676,42 @@ static int hvfb_getmem(struct fb_info *info)
 	if (!info->apertures)
 		goto err3;
 
-	info->apertures->ranges[0].base = pci_resource_start(pdev, 0);
-	info->apertures->ranges[0].size = pci_resource_len(pdev, 0);
-	info->fix.smem_start = fb_phys;
+	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);
+	}
+
+	info->fix.smem_start = par->mem.start;
 	info->fix.smem_len = screen_fb_size;
 	info->screen_base = fb_virt;
 	info->screen_size = screen_fb_size;
 
-	pci_dev_put(pdev);
+	if (!gen2vm)
+		pci_dev_put(pdev);
+
 	return 0;
 
 err3:
 	iounmap(fb_virt);
 err2:
-	release_mem_region(fb_phys, screen_fb_size);
+	release_resource(&par->mem);
 err1:
-	pci_dev_put(pdev);
+	if (!gen2vm)
+		pci_dev_put(pdev);
+
 	return -ENOMEM;
 }
 
 /* Release the framebuffer */
 static void hvfb_putmem(struct fb_info *info)
 {
+	struct hvfb_par *par = info->par;
+
 	iounmap(info->screen_base);
-	release_mem_region(info->fix.smem_start, screen_fb_size);
+	release_resource(&par->mem);
 }