1 files changed, 280 insertions, 0 deletions
diff --git a/arch/x86/kernel/probe_roms.c b/arch/x86/kernel/probe_roms.c
new file mode 100644
index 000000000..319fef37d
--- /dev/null
+++ b/arch/x86/kernel/probe_roms.c
@@ -0,0 +1,280 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/uaccess.h>
+#include <linux/mmzone.h>
+#include <linux/ioport.h>
+#include <linux/seq_file.h>
+#include <linux/console.h>
+#include <linux/init.h>
+#include <linux/edd.h>
+#include <linux/dmi.h>
+#include <linux/pfn.h>
+#include <linux/pci.h>
+#include <linux/export.h>
+
+#include <asm/probe_roms.h>
+#include <asm/pci-direct.h>
+#include <asm/e820/api.h>
+#include <asm/mmzone.h>
+#include <asm/setup.h>
+#include <asm/sections.h>
+#include <asm/io.h>
+#include <asm/setup_arch.h>
+#include <asm/sev.h>
+
+static struct resource system_rom_resource = {
+	.name	= "System ROM",
+	.start	= 0xf0000,
+	.end	= 0xfffff,
+	.flags	= IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
+};
+
+static struct resource extension_rom_resource = {
+	.name	= "Extension ROM",
+	.start	= 0xe0000,
+	.end	= 0xeffff,
+	.flags	= IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
+};
+
+static struct resource adapter_rom_resources[] = { {
+	.name 	= "Adapter ROM",
+	.start	= 0xc8000,
+	.end	= 0,
+	.flags	= IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
+}, {
+	.name 	= "Adapter ROM",
+	.start	= 0,
+	.end	= 0,
+	.flags	= IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
+}, {
+	.name 	= "Adapter ROM",
+	.start	= 0,
+	.end	= 0,
+	.flags	= IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
+}, {
+	.name 	= "Adapter ROM",
+	.start	= 0,
+	.end	= 0,
+	.flags	= IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
+}, {
+	.name 	= "Adapter ROM",
+	.start	= 0,
+	.end	= 0,
+	.flags	= IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
+}, {
+	.name 	= "Adapter ROM",
+	.start	= 0,
+	.end	= 0,
+	.flags	= IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
+} };
+
+static struct resource video_rom_resource = {
+	.name 	= "Video ROM",
+	.start	= 0xc0000,
+	.end	= 0xc7fff,
+	.flags	= IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
+};
+
+/* does this oprom support the given pci device, or any of the devices
+ * that the driver supports?
+ */
+static bool match_id(struct pci_dev *pdev, unsigned short vendor, unsigned short device)
+{
+	struct pci_driver *drv = to_pci_driver(pdev->dev.driver);
+	const struct pci_device_id *id;
+
+	if (pdev->vendor == vendor && pdev->device == device)
+		return true;
+
+	for (id = drv ? drv->id_table : NULL; id && id->vendor; id++)
+		if (id->vendor == vendor && id->device == device)
+			break;
+
+	return id && id->vendor;
+}
+
+static bool probe_list(struct pci_dev *pdev, unsigned short vendor,
+		       const void *rom_list)
+{
+	unsigned short device;
+
+	do {
+		if (get_kernel_nofault(device, rom_list) != 0)
+			device = 0;
+
+		if (device && match_id(pdev, vendor, device))
+			break;
+
+		rom_list += 2;
+	} while (device);
+
+	return !!device;
+}
+
+static struct resource *find_oprom(struct pci_dev *pdev)
+{
+	struct resource *oprom = NULL;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(adapter_rom_resources); i++) {
+		struct resource *res = &adapter_rom_resources[i];
+		unsigned short offset, vendor, device, list, rev;
+		const void *rom;
+
+		if (res->end == 0)
+			break;
+
+		rom = isa_bus_to_virt(res->start);
+		if (get_kernel_nofault(offset, rom + 0x18) != 0)
+			continue;
+
+		if (get_kernel_nofault(vendor, rom + offset + 0x4) != 0)
+			continue;
+
+		if (get_kernel_nofault(device, rom + offset + 0x6) != 0)
+			continue;
+
+		if (match_id(pdev, vendor, device)) {
+			oprom = res;
+			break;
+		}
+
+		if (get_kernel_nofault(list, rom + offset + 0x8) == 0 &&
+		    get_kernel_nofault(rev, rom + offset + 0xc) == 0 &&
+		    rev >= 3 && list &&
+		    probe_list(pdev, vendor, rom + offset + list)) {
+			oprom = res;
+			break;
+		}
+	}
+
+	return oprom;
+}
+
+void __iomem *pci_map_biosrom(struct pci_dev *pdev)
+{
+	struct resource *oprom = find_oprom(pdev);
+
+	if (!oprom)
+		return NULL;
+
+	return ioremap(oprom->start, resource_size(oprom));
+}
+EXPORT_SYMBOL(pci_map_biosrom);
+
+void pci_unmap_biosrom(void __iomem *image)
+{
+	iounmap(image);
+}
+EXPORT_SYMBOL(pci_unmap_biosrom);
+
+size_t pci_biosrom_size(struct pci_dev *pdev)
+{
+	struct resource *oprom = find_oprom(pdev);
+
+	return oprom ? resource_size(oprom) : 0;
+}
+EXPORT_SYMBOL(pci_biosrom_size);
+
+#define ROMSIGNATURE 0xaa55
+
+static int __init romsignature(const unsigned char *rom)
+{
+	const unsigned short * const ptr = (const unsigned short *)rom;
+	unsigned short sig;
+
+	return get_kernel_nofault(sig, ptr) == 0 && sig == ROMSIGNATURE;
+}
+
+static int __init romchecksum(const unsigned char *rom, unsigned long length)
+{
+	unsigned char sum, c;
+
+	for (sum = 0; length && get_kernel_nofault(c, rom++) == 0; length--)
+		sum += c;
+	return !length && !sum;
+}
+
+void __init probe_roms(void)
+{
+	unsigned long start, length, upper;
+	const unsigned char *rom;
+	unsigned char c;
+	int i;
+
+	/*
+	 * The ROM memory range is not part of the e820 table and is therefore not
+	 * pre-validated by BIOS. The kernel page table maps the ROM region as encrypted
+	 * memory, and SNP requires encrypted memory to be validated before access.
+	 * Do that here.
+	 */
+	snp_prep_memory(video_rom_resource.start,
+			((system_rom_resource.end + 1) - video_rom_resource.start),
+			SNP_PAGE_STATE_PRIVATE);
+
+	/* video rom */
+	upper = adapter_rom_resources[0].start;
+	for (start = video_rom_resource.start; start < upper; start += 2048) {
+		rom = isa_bus_to_virt(start);
+		if (!romsignature(rom))
+			continue;
+
+		video_rom_resource.start = start;
+
+		if (get_kernel_nofault(c, rom + 2) != 0)
+			continue;
+
+		/* 0 < length <= 0x7f * 512, historically */
+		length = c * 512;
+
+		/* if checksum okay, trust length byte */
+		if (length && romchecksum(rom, length))
+			video_rom_resource.end = start + length - 1;
+
+		request_resource(&iomem_resource, &video_rom_resource);
+		break;
+	}
+
+	start = (video_rom_resource.end + 1 + 2047) & ~2047UL;
+	if (start < upper)
+		start = upper;
+
+	/* system rom */
+	request_resource(&iomem_resource, &system_rom_resource);
+	upper = system_rom_resource.start;
+
+	/* check for extension rom (ignore length byte!) */
+	rom = isa_bus_to_virt(extension_rom_resource.start);
+	if (romsignature(rom)) {
+		length = resource_size(&extension_rom_resource);
+		if (romchecksum(rom, length)) {
+			request_resource(&iomem_resource, &extension_rom_resource);
+			upper = extension_rom_resource.start;
+		}
+	}
+
+	/* check for adapter roms on 2k boundaries */
+	for (i = 0; i < ARRAY_SIZE(adapter_rom_resources) && start < upper; start += 2048) {
+		rom = isa_bus_to_virt(start);
+		if (!romsignature(rom))
+			continue;
+
+		if (get_kernel_nofault(c, rom + 2) != 0)
+			continue;
+
+		/* 0 < length <= 0x7f * 512, historically */
+		length = c * 512;
+
+		/* but accept any length that fits if checksum okay */
+		if (!length || start + length > upper || !romchecksum(rom, length))
+			continue;
+
+		adapter_rom_resources[i].start = start;
+		adapter_rom_resources[i].end = start + length - 1;
+		request_resource(&iomem_resource, &adapter_rom_resources[i]);
+
+		start = adapter_rom_resources[i++].end & ~2047UL;
+	}
+}
+