On Tue, Jan 10, 2023 at 10:29:06AM -0800, Dan Williams wrote: > Bjorn Helgaas wrote: > > From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > > > > 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 PCI 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. > > > > Reported by Kan Liang, Tony Luck, and Giovanni Cabiddu. > > > > Fixes: 07eab0901ede ("efi/x86: Remove EfiMemoryMappedIO from E820 map") > > Link: https://lore.kernel.org/r/ac2693d8-8ba3-72e0-5b66-b3ae008d539d@xxxxxxxxxxxxxxx > > Reported-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx> > > Reported-by: Tony Luck <tony.luck@xxxxxxxxx> > > Reported-by: Giovanni Cabiddu <giovanni.cabiddu@xxxxxxxxx> > > Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > > --- > > arch/x86/pci/mmconfig-shared.c | 31 +++++++++++++++++++++++++++++++ > > 1 file changed, 31 insertions(+) > > > > diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c > > index cd16bef5f2d9..da4b6e8e9df0 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 +443,32 @@ 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) > > +{ > > +#ifdef CONFIG_EFI > > + efi_memory_desc_t *md; > > + u64 size, mmio_start, mmio_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; > > + > > + /* > > + * N.B. Caller supplies (start, start + size), > > + * so to match, mmio_end is the first address > > + * *past* the EFI_MEMORY_MAPPED_IO area. > > + */ > > + if (mmio_start <= start && end <= mmio_end) > > + return true; > > + } > > + } > > +#endif > > Perhaps the following trick (compile tested), but either way: > > Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx> That's a great trick, and I wish I'd thought of it. I have some follow-on patches I'm considering for v6.3, so in the interest of streamlining the path of this one to v6.2-rc4, I think I'll wait on this until v6.3. > diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c > index da4b6e8e9df0..ae95d1b073c6 100644 > --- a/arch/x86/pci/mmconfig-shared.c > +++ b/arch/x86/pci/mmconfig-shared.c > @@ -445,7 +445,6 @@ static bool is_acpi_reserved(u64 start, u64 end, enum e820_type not_used) > > static bool is_efi_mmio(u64 start, u64 end, enum e820_type not_used) > { > -#ifdef CONFIG_EFI > efi_memory_desc_t *md; > u64 size, mmio_start, mmio_end; > > @@ -464,7 +463,6 @@ static bool is_efi_mmio(u64 start, u64 end, enum e820_type not_used) > return true; > } > } > -#endif > > return false; > } > diff --git a/include/linux/efi.h b/include/linux/efi.h > index 4b27519143f5..3ab0c255b791 100644 > --- a/include/linux/efi.h > +++ b/include/linux/efi.h > @@ -790,8 +790,12 @@ extern int efi_memattr_apply_permissions(struct mm_struct *mm, > * > * Once the loop finishes @md must not be accessed. > */ > +#ifdef CONFIG_EFI > #define for_each_efi_memory_desc(md) \ > for_each_efi_memory_desc_in_map(&efi.memmap, md) > +#else > +#define for_each_efi_memory_desc(md) for (; 0;) > +#endif > > /* > * Format an EFI memory descriptor's type and attributes to a user-provided