Re: Bug report: the extended PCI config space is missed with 6.2-rc2

[Bjorn Helgaas]

On Fri, Jan 06, 2023 at 09:37:06PM +0000, Luck, Tony wrote:
> > Thanks, Tony!  Something is wrong with the EFI MMIO removal
> > (obviously), but I don't see what it is.  Could you try the patch
> > below (replacement for previous one, with more debug)?
> 
> Swapped out old patch for this new one. Booted with efi-debug
> 
> New dmesg attached.

Thanks!  Ah, off-by-one error because e820__mapped_all() expects
"[start, end)" which means is_acpi_reserved() and is_efi_mmio() must
use the same, and I was thinking "[start, end]" like a struct
resource.

The below should work better.

commit 696ac9286d3d ("x86/pci: Treat EfiMemoryMappedIO as reservation of ECAM space")
parent 1b929c02afd3
Author: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Date:   Thu Jan 5 16:02:58 2023 -0600

    x86/pci: Treat EfiMemoryMappedIO as reservation of ECAM space
    
    Normally we reject ECAM space unless it is reported as reserved in the E820
    table or via a PNP0C02 _CRS method (PCI Firmware, r3.3, sec 4.1.2).  This
    means extended config space (offsets 0x100-0xfff) may not be accessible.
    
    Some firmware doesn't report ECAM space via PNP0C02 _CRS methods, but does
    mention it as an EfiMemoryMappedIO region via EFI GetMemoryMap(), which is
    normally converted to an E820 entry by a bootloader or EFI stub.
    
    07eab0901ede ("efi/x86: Remove EfiMemoryMappedIO from E820 map"), removes
    E820 entries that correspond to EfiMemoryMappedIO regions because some
    other firmware uses EfiMemoryMappedIO for PCI host bridge windows, and the
    E820 entries prevent Linux from allocating BAR space for hot-added devices.
    
    Allow use of ECAM for extended config space when the region is covered by
    an EfiMemoryMappedIO region, even if it's not included in E820 or PNP0C02
    _CRS.
    
    Fixes: 07eab0901ede ("efi/x86: Remove EfiMemoryMappedIO from E820 map")
    Link: https://lore.kernel.org/r/ac2693d8-8ba3-72e0-5b66-b3ae008d539d@xxxxxxxxxxxxxxx

diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c
index 758cbfe55daa..5c6cadd60fef 100644
--- a/arch/x86/pci/mmconfig-shared.c
+++ b/arch/x86/pci/mmconfig-shared.c
@@ -12,6 +12,7 @@
  */
 
 #include <linux/acpi.h>
+#include <linux/efi.h>
 #include <linux/pci.h>
 #include <linux/init.h>
 #include <linux/bitmap.h>
@@ -442,6 +443,34 @@ static bool is_acpi_reserved(u64 start, u64 end, enum e820_type not_used)
 	return mcfg_res.flags;
 }
 
+static bool is_efi_mmio(u64 start, u64 end, enum e820_type not_used)
+{
+	efi_memory_desc_t *md;
+	u64 size, mmio_start, mmio_end;
+
+	end--;		/* caller supplies start, end = start + size */
+	pr_info("is_efi_mmio %#lx-%#lx\n",
+		(unsigned long) start, (unsigned long) end);
+	for_each_efi_memory_desc(md) {
+		if (md->type == EFI_MEMORY_MAPPED_IO) {
+			size = md->num_pages << EFI_PAGE_SHIFT;
+			mmio_start = md->phys_addr;
+			mmio_end = mmio_start + size - 1;
+
+			pr_info("  efi_mmio %#lx-%#lx\n",
+				(unsigned long) mmio_start,
+				(unsigned long) mmio_end);
+			if (mmio_start <= start && end <= mmio_end) {
+				pr_info("is_efi_mmio true\n");
+				return true;
+			}
+		}
+	}
+
+	pr_info("is_efi_mmio false\n");
+	return false;
+}
+
 typedef bool (*check_reserved_t)(u64 start, u64 end, enum e820_type type);
 
 static bool __ref is_mmconf_reserved(check_reserved_t is_reserved,
@@ -452,23 +481,24 @@ static bool __ref is_mmconf_reserved(check_reserved_t is_reserved,
 	u64 size = resource_size(&cfg->res);
 	u64 old_size = size;
 	int num_buses;
-	char *method = with_e820 ? "E820" : "ACPI motherboard resources";
+	char *method = with_e820 ? "E820" : "ACPI motherboard resources or EFI";
 
+	pr_info("is_mmconf_reserved %ps [bus %02x-%02x] %pR\n",
+		is_reserved, cfg->start_bus, cfg->end_bus, &cfg->res);
 	while (!is_reserved(addr, addr + size, E820_TYPE_RESERVED)) {
+		pr_info("  %#lx-%#lx (size %#lx) not reserved\n",
+			(unsigned long) addr, (unsigned long) (addr + size - 1),
+			(unsigned long) size);
 		size >>= 1;
+		pr_info("  size reduced to %#lx\n", (unsigned long) size);
 		if (size < (16UL<<20))
 			break;
 	}
 
-	if (size < (16UL<<20) && size != old_size)
+	if (size < (16UL<<20) && size != old_size) {
+		pr_info("is_mmconf_reserved %ps false\n", is_reserved);
 		return false;
-
-	if (dev)
-		dev_info(dev, "MMCONFIG at %pR reserved in %s\n",
-			 &cfg->res, method);
-	else
-		pr_info(PREFIX "MMCONFIG at %pR reserved in %s\n",
-		       &cfg->res, method);
+	}
 
 	if (old_size != size) {
 		/* update end_bus */
@@ -487,30 +517,42 @@ static bool __ref is_mmconf_reserved(check_reserved_t is_reserved,
 				&cfg->res, (unsigned long) cfg->address);
 		else
 			pr_info(PREFIX
-				"MMCONFIG for %04x [bus%02x-%02x] "
+				"MMCONFIG for %04x [bus %02x-%02x] "
 				"at %pR (base %#lx) (size reduced!)\n",
 				cfg->segment, cfg->start_bus, cfg->end_bus,
 				&cfg->res, (unsigned long) cfg->address);
 	}
 
+	if (dev)
+		dev_info(dev, "MMCONFIG at %pR reserved in %s\n",
+			 &cfg->res, method);
+	else
+		pr_info(PREFIX "MMCONFIG at %pR reserved in %s\n",
+		       &cfg->res, method);
+
 	return true;
 }
 
 static bool __ref
 pci_mmcfg_check_reserved(struct device *dev, struct pci_mmcfg_region *cfg, int early)
 {
+	pr_info("pci_mmcfg_check_reserved([bus %02x-%02x] %pR, %s)\n",
+		cfg->start_bus, cfg->end_bus, &cfg->res,
+		early ? "early" : "late");
 	if (!early && !acpi_disabled) {
 		if (is_mmconf_reserved(is_acpi_reserved, cfg, dev, 0))
 			return true;
+		if (is_mmconf_reserved(is_efi_mmio, cfg, dev, 0))
+			return true;
 
 		if (dev)
 			dev_info(dev, FW_INFO
-				 "MMCONFIG at %pR not reserved in "
+				 "MMCONFIG at %pR not reserved in EFI or "
 				 "ACPI motherboard resources\n",
 				 &cfg->res);
 		else
 			pr_info(FW_INFO PREFIX
-			       "MMCONFIG at %pR not reserved in "
+			       "MMCONFIG at %pR not reserved in EFI or "
 			       "ACPI motherboard resources\n",
 			       &cfg->res);
 	}
@@ -536,6 +578,7 @@ static void __init pci_mmcfg_reject_broken(int early)
 {
 	struct pci_mmcfg_region *cfg;
 
+	pr_info("pci_mmcfg_reject_broken(%s)\n", early ? "early" : "late");
 	list_for_each_entry(cfg, &pci_mmcfg_list, list) {
 		if (pci_mmcfg_check_reserved(NULL, cfg, early) == 0) {
 			pr_info(PREFIX "not using MMCONFIG\n");
@@ -570,6 +613,7 @@ static int __init pci_parse_mcfg(struct acpi_table_header *header)
 	unsigned long i;
 	int entries;
 
+	pr_info("pci_parse_mcfg\n");
 	if (!header)
 		return -EINVAL;
 
@@ -661,6 +705,7 @@ static int __initdata known_bridge;
 
 void __init pci_mmcfg_early_init(void)
 {
+	pr_info("pci_mmcfg_early_init\n");
 	if (pci_probe & PCI_PROBE_MMCONF) {
 		if (pci_mmcfg_check_hostbridge())
 			known_bridge = 1;
@@ -674,6 +719,7 @@ void __init pci_mmcfg_early_init(void)
 
 void __init pci_mmcfg_late_init(void)
 {
+	pr_info("pci_mmcfg_late_init\n");
 	/* MMCONFIG disabled */
 	if ((pci_probe & PCI_PROBE_MMCONF) == 0)
 		return;
@@ -725,6 +771,8 @@ int pci_mmconfig_insert(struct device *dev, u16 seg, u8 start, u8 end,
 	struct resource *tmp = NULL;
 	struct pci_mmcfg_region *cfg;
 
+	dev_info(dev, "pci_mmconfig_insert %02x-%02x addr %#lx\n",
+		 start, end, (unsigned long)addr);
 	if (!(pci_probe & PCI_PROBE_MMCONF) || pci_mmcfg_arch_init_failed)
 		return -ENODEV;
 
@@ -788,6 +836,7 @@ int pci_mmconfig_insert(struct device *dev, u16 seg, u8 start, u8 end,
 
 	mutex_unlock(&pci_mmcfg_lock);
 
+	dev_info(dev, "pci_mmconfig_insert returns %d\n", rc);
 	return rc;
 }