Hi, On 6/14/22 01:15, Bjorn Helgaas wrote: > On Sun, Jun 12, 2022 at 04:43:25PM +0200, Hans de Goede wrote: >> Clipping the bridge windows directly from pci_acpi_root_prepare_resources() >> instead of clipping from arch_remove_reservations(), has a number of >> unforseen consequences. >> >> If there is an e820 reservation in the middle of a bridge window, then >> the smallest of the 2 remaining parts of the window will be also clipped >> off. Where as the previous code would clip regions requested by devices, >> rather then the entire window, leaving regions which were either entirely >> above or below a reservation in the middle of the window alone. >> >> E.g. on the Steam Deck this leads to this log message: >> >> acpi PNP0A08:00: clipped [mem 0x80000000-0xf7ffffff window] to [mem 0xa0100000-0xf7ffffff window] >> >> which then gets followed by these log messages: >> >> pci 0000:00:01.2: can't claim BAR 14 [mem 0x80600000-0x806fffff]: no compatible bridge window >> pci 0000:00:01.3: can't claim BAR 14 [mem 0x80500000-0x805fffff]: no compatible bridge window >> >> and many more of these. Ultimately this leads to the Steam Deck >> no longer booting properly, so revert the change. >> >> Note this is not a clean revert, this revert keeps the later change >> to make the clipping dependent on a new pci_use_e820 bool, moving >> the checking of this bool to arch_remove_reservations(). > > 4c5e242d3e93 was definitely a mistake (my fault). My intent was to > mainly to improve logging of the clipping, but I didn't implement it > well. > > That said, I'd like to understand the connection between the messages > you mention and the failure. There are four bridges whose MMIO > windows were in the [mem 0x80000000-0x9fffffff] area that we clipped > out. The log shows that we moved all those windows and the devices in > them to the [mem 0xa0100000-0xf7ffffff] area that remained after > clipping. > > So I think this *should* have worked even though we moved things > around unnecessarily. What am I missing? I don't know? My guess is that maybe the ACPI table do MMIO accesses somewhere to hardcoded addresses and moving things breaks the ACPI tables. > > The E820 map reports [mem 0xa0000000-0xa00fffff] in the middle of the > _CRS, and we currently trim that out. We think this is a firmware > defect, so it's likely to break in 2023 if we stop clipping by > default. I'm concerned that there may be other things in _CRS that we > need to avoid, but firmware isn't telling us about them. > > Or there's some dependency in the devices that we moved on their > original addresses, e.g., firmware on the device latched the address > and didn't notice the reassignment. Right this is the most likely cause I believe. Regards, Hans > > [1] https://bugzilla.kernel.org/attachment.cgi?id=301154 > >> BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=216109 >> Fixes: 4c5e242d3e93 ("x86/PCI: Clip only host bridge windows for E820 regions") >> Reported-and-tested-by: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxx> >> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> >> --- >> arch/x86/include/asm/e820/api.h | 5 ----- >> arch/x86/include/asm/pci_x86.h | 8 ++++++++ >> arch/x86/kernel/resource.c | 14 +++++++++----- >> arch/x86/pci/acpi.c | 8 +------- >> 4 files changed, 18 insertions(+), 17 deletions(-) >> >> diff --git a/arch/x86/include/asm/e820/api.h b/arch/x86/include/asm/e820/api.h >> index 5a39ed59b6db..e8f58ddd06d9 100644 >> --- a/arch/x86/include/asm/e820/api.h >> +++ b/arch/x86/include/asm/e820/api.h >> @@ -4,9 +4,6 @@ >> >> #include <asm/e820/types.h> >> >> -struct device; >> -struct resource; >> - >> extern struct e820_table *e820_table; >> extern struct e820_table *e820_table_kexec; >> extern struct e820_table *e820_table_firmware; >> @@ -46,8 +43,6 @@ extern void e820__register_nosave_regions(unsigned long limit_pfn); >> >> extern int e820__get_entry_type(u64 start, u64 end); >> >> -extern void remove_e820_regions(struct device *dev, struct resource *avail); >> - >> /* >> * Returns true iff the specified range [start,end) is completely contained inside >> * the ISA region. >> diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h >> index f52a886d35cf..70533fdcbf02 100644 >> --- a/arch/x86/include/asm/pci_x86.h >> +++ b/arch/x86/include/asm/pci_x86.h >> @@ -69,6 +69,8 @@ void pcibios_scan_specific_bus(int busn); >> >> /* pci-irq.c */ >> >> +struct pci_dev; >> + >> struct irq_info { >> u8 bus, devfn; /* Bus, device and function */ >> struct { >> @@ -246,3 +248,9 @@ static inline void mmio_config_writel(void __iomem *pos, u32 val) >> # define x86_default_pci_init_irq NULL >> # define x86_default_pci_fixup_irqs NULL >> #endif >> + >> +#if defined(CONFIG_PCI) && defined(CONFIG_ACPI) >> +extern bool pci_use_e820; >> +#else >> +#define pci_use_e820 false >> +#endif >> diff --git a/arch/x86/kernel/resource.c b/arch/x86/kernel/resource.c >> index db2b350a37b7..bba1abd05bfe 100644 >> --- a/arch/x86/kernel/resource.c >> +++ b/arch/x86/kernel/resource.c >> @@ -1,7 +1,8 @@ >> // SPDX-License-Identifier: GPL-2.0 >> -#include <linux/dev_printk.h> >> #include <linux/ioport.h> >> +#include <linux/printk.h> >> #include <asm/e820/api.h> >> +#include <asm/pci_x86.h> >> >> static void resource_clip(struct resource *res, resource_size_t start, >> resource_size_t end) >> @@ -24,14 +25,14 @@ static void resource_clip(struct resource *res, resource_size_t start, >> res->start = end + 1; >> } >> >> -void remove_e820_regions(struct device *dev, struct resource *avail) >> +static void remove_e820_regions(struct resource *avail) >> { >> int i; >> struct e820_entry *entry; >> u64 e820_start, e820_end; >> struct resource orig = *avail; >> >> - if (!(avail->flags & IORESOURCE_MEM)) >> + if (!pci_use_e820) >> return; >> >> for (i = 0; i < e820_table->nr_entries; i++) { >> @@ -41,7 +42,7 @@ void remove_e820_regions(struct device *dev, struct resource *avail) >> >> resource_clip(avail, e820_start, e820_end); >> if (orig.start != avail->start || orig.end != avail->end) { >> - dev_info(dev, "clipped %pR to %pR for e820 entry [mem %#010Lx-%#010Lx]\n", >> + pr_info("clipped %pR to %pR for e820 entry [mem %#010Lx-%#010Lx]\n", >> &orig, avail, e820_start, e820_end); >> orig = *avail; >> } >> @@ -55,6 +56,9 @@ void arch_remove_reservations(struct resource *avail) >> * the low 1MB unconditionally, as this area is needed for some ISA >> * cards requiring a memory range, e.g. the i82365 PCMCIA controller. >> */ >> - if (avail->flags & IORESOURCE_MEM) >> + if (avail->flags & IORESOURCE_MEM) { >> resource_clip(avail, BIOS_ROM_BASE, BIOS_ROM_END); >> + >> + remove_e820_regions(avail); >> + } >> } >> diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c >> index a4f43054bc79..2f82480fd430 100644 >> --- a/arch/x86/pci/acpi.c >> +++ b/arch/x86/pci/acpi.c >> @@ -8,7 +8,6 @@ >> #include <linux/pci-acpi.h> >> #include <asm/numa.h> >> #include <asm/pci_x86.h> >> -#include <asm/e820/api.h> >> >> struct pci_root_info { >> struct acpi_pci_root_info common; >> @@ -20,7 +19,7 @@ struct pci_root_info { >> #endif >> }; >> >> -static bool pci_use_e820 = true; >> +bool pci_use_e820 = true; >> static bool pci_use_crs = true; >> static bool pci_ignore_seg; >> >> @@ -387,11 +386,6 @@ static int pci_acpi_root_prepare_resources(struct acpi_pci_root_info *ci) >> >> status = acpi_pci_probe_root_resources(ci); >> >> - if (pci_use_e820) { >> - resource_list_for_each_entry(entry, &ci->resources) >> - remove_e820_regions(&device->dev, entry->res); >> - } >> - >> if (pci_use_crs) { >> resource_list_for_each_entry_safe(entry, tmp, &ci->resources) >> if (resource_is_pcicfg_ioport(entry->res)) >> -- >> 2.36.0 >> >
