| Message ID | 20210624095324.34906-1-hui.wang@canonical.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | x86/PCI: Conditionally add a non-e820 mapped window to root bridge | expand |
[+cc Myron, just FYI] On Thu, Jun 24, 2021 at 05:53:24PM +0800, Hui Wang wrote: > The touchpad can't work on many Lenovo Ideapad S145/BS145 laptops. > But it works well under Windows. > > On those machines, the touchpad is an I2C device, while the I2C host > controllers fail to initialize as below shown: > pci 0000:00:15.0: BAR 0: no space for [mem size 0x00001000 64bit] > pci 0000:00:15.0: BAR 0: failed to assign [mem size 0x00001000 64bit] > pci 0000:00:15.1: BAR 0: no space for [mem size 0x00001000 64bit] > pci 0000:00:15.1: BAR 0: failed to assign [mem size 0x00001000 64bit] > > The BIOS assigns iomem space to host bridge and I2C host controller > like this: > pci_bus 0000:00: root bus resource [mem 0x000a0000-0x000bffff window] > pci_bus 0000:00: root bus resource [mem 0x65400000-0xbfffffff window] > > pci 0000:00:15.0: [8086:34e8] type 00 class 0x0c8000 > pci 0000:00:15.0: reg 0x10: [mem 0x00000000-0x00000fff 64bit] > pci 0000:00:15.1: [8086:34e9] type 00 class 0x0c8000 > pci 0000:00:15.1: reg 0x10: [mem 0x00000000-0x00000fff 64bit] > > The I2C host controllers need to allocate iomem space from root > bridge, but all iomem window of the root bridge are overlapped with > BIOS-e820 mapped region, that makes the allocate_resource() fail: > BIOS-e820: [mem 0x0000000000000000-0x000000000009efff] usable > BIOS-e820: [mem 0x000000000009f000-0x00000000000fffff] reserved > ... > BIOS-e820: [mem 0x000000004bc50000-0x00000000cfffffff] reserved > > We could add "pci=nocrs" to make the touchpad work, but users expect > the touchpad to work out-of-box under Linux distro as under Windows. > > Here design a generic solution for x86 machines, if host bridge uses > crs, we will check if all root bridge iomem windows are overlapped > with BIOS-e820 mapped region, if yes, we try to build a non-e820 > mapped window according to the biggest gap in the e820 mapped region, > and we need to clip this window with MMCONFIG region if this region > is not mapped by BIOS-e820, then insert this window to the tail of > the root bridge. > > After this change, the I2C host controller could allocate the iomem > region from host bridge successfully and the touchpad could work > out-of-box. I see from https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1931715 that a fix has been committed, I assume to the Ubuntu kernel, but I assume this is still a problem for upstream and probably other distro kernels. The 0-day bot found some issue, which I haven't looked at: https://lore.kernel.org/r/20210627143859.GD17986@xsang-OptiPlex-9020 I think this patch might be the wrong approach. We learned from _CRS that [mem 0x65400000-0xbfffffff window] is assigned to the PNP0A08:00 host bridge. The e820 "[mem 0x000000004bc50000-0x00000000cfffffff] reserved" region certainly includes all of that PCI aperture, and this entry should prevent that space from being allocated to devices that haven't already been assigned space. But I don't think that e820 entry should prevent the PCI core from managing that PCI aperture. The platform told us that PNP0A08:00 owns the [mem 0x65400000-0xbfffffff window], and the PNP0A08:00 driver (pci_root.c) should be able to manage it as needed. > BugLink: http://bugs.launchpad.net/bugs/1931715 > BugLink: http://bugs.launchpad.net/bugs/1932069 > BugLink: http://bugs.launchpad.net/bugs/1921649 > Cc: Bjorn Helgaas <bhelgaas@google.com> > Cc: Yinghai Lu <yinghai@kernel.org> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > Cc: linux-acpi@vger.kernel.org > Cc: linux-pci@vger.kernel.org > Signed-off-by: Hui Wang <hui.wang@canonical.com> > --- > arch/x86/include/asm/e820/api.h | 1 + > arch/x86/include/asm/pci.h | 2 ++ > arch/x86/include/asm/pci_x86.h | 1 + > arch/x86/kernel/e820.c | 2 ++ > arch/x86/pci/acpi.c | 46 ++++++++++++++++++++++++++++++++- > arch/x86/pci/mmconfig-shared.c | 28 ++++++++++++++++++++ > 6 files changed, 79 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/include/asm/e820/api.h b/arch/x86/include/asm/e820/api.h > index e8f58ddd06d9..46c76201dc28 100644 > --- a/arch/x86/include/asm/e820/api.h > +++ b/arch/x86/include/asm/e820/api.h > @@ -9,6 +9,7 @@ extern struct e820_table *e820_table_kexec; > extern struct e820_table *e820_table_firmware; > > extern unsigned long pci_mem_start; > +extern unsigned long pci_mem_gap_size; > > extern bool e820__mapped_raw_any(u64 start, u64 end, enum e820_type type); > extern bool e820__mapped_any(u64 start, u64 end, enum e820_type type); > diff --git a/arch/x86/include/asm/pci.h b/arch/x86/include/asm/pci.h > index d2c76c8d8cfd..a940a792ef7b 100644 > --- a/arch/x86/include/asm/pci.h > +++ b/arch/x86/include/asm/pci.h > @@ -81,6 +81,8 @@ static inline int pcibios_assign_all_busses(void) { return 0; } > #endif > > extern unsigned long pci_mem_start; > +extern unsigned long pci_mem_gap_size; > + > #define PCIBIOS_MIN_IO 0x1000 > #define PCIBIOS_MIN_MEM (pci_mem_start) > > diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h > index 490411dba438..3ea30aed9100 100644 > --- a/arch/x86/include/asm/pci_x86.h > +++ b/arch/x86/include/asm/pci_x86.h > @@ -171,6 +171,7 @@ extern int pci_mmconfig_delete(u16 seg, u8 start, u8 end); > extern struct pci_mmcfg_region *pci_mmconfig_lookup(int segment, int bus); > extern struct pci_mmcfg_region *__init pci_mmconfig_add(int segment, int start, > int end, u64 addr); > +extern void pci_mmconfig_clip_resource(struct resource *res); > > extern struct list_head pci_mmcfg_list; > > diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c > index bc0657f0deed..2933745b19b7 100644 > --- a/arch/x86/kernel/e820.c > +++ b/arch/x86/kernel/e820.c > @@ -66,6 +66,7 @@ struct e820_table *e820_table_firmware __refdata = &e820_table_firmware_init; > > /* For PCI or other memory-mapped resources */ > unsigned long pci_mem_start = 0xaeedbabe; > +unsigned long pci_mem_gap_size; > #ifdef CONFIG_PCI > EXPORT_SYMBOL(pci_mem_start); > #endif > @@ -677,6 +678,7 @@ __init void e820__setup_pci_gap(void) > * e820__reserve_resources_late() protects stolen RAM already: > */ > pci_mem_start = gapstart; > + pci_mem_gap_size = gapsize; > > pr_info("[mem %#010lx-%#010lx] available for PCI devices\n", > gapstart, gapstart + gapsize - 1); > diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c > index 948656069cdd..e3a691024683 100644 > --- a/arch/x86/pci/acpi.c > +++ b/arch/x86/pci/acpi.c > @@ -231,6 +231,11 @@ static void teardown_mcfg_map(struct acpi_pci_root_info *ci) > info->mcfg_added = false; > } > } > + > +static void clip_resource_from_mmcfg(struct resource *res) > +{ > + return pci_mmconfig_clip_resource(res); > +} > #else > static int setup_mcfg_map(struct acpi_pci_root_info *ci) > { > @@ -240,6 +245,10 @@ static int setup_mcfg_map(struct acpi_pci_root_info *ci) > static void teardown_mcfg_map(struct acpi_pci_root_info *ci) > { > } > + > +static void clip_resource_from_mmcfg(struct resource *res) > +{ > +} > #endif > > static int pci_acpi_root_get_node(struct acpi_pci_root *root) > @@ -296,13 +305,48 @@ static int pci_acpi_root_prepare_resources(struct acpi_pci_root_info *ci) > struct acpi_device *device = ci->bridge; > int busnum = ci->root->secondary.start; > struct resource_entry *entry, *tmp; > + bool has_non_e820_region = false; > int status; > > status = acpi_pci_probe_root_resources(ci); > if (pci_use_crs) { > - resource_list_for_each_entry_safe(entry, tmp, &ci->resources) > + resource_list_for_each_entry_safe(entry, tmp, &ci->resources) { > + struct resource avail = *entry->res; > + > if (resource_is_pcicfg_ioport(entry->res)) > resource_list_destroy_entry(entry); > + > + if (avail.flags & IORESOURCE_MEM) { > + arch_remove_reservations(&avail); > + if (avail.end > avail.start) > + has_non_e820_region = true; > + } > + } > + > + /* all bridge windows are in the BIOS-e820 mapped region, this > + * will make allocate_resource() fail when PCI devices request > + * iomem address from bridge. To fix it, we try to build a non > + * e820 mapped iomem resource and clip it with MMCONFIG region, > + * then add it to the bridge window list. > + */ > + if (!has_non_e820_region) { > + struct resource_entry *rentry; > + struct resource avail; > + > + avail.start = pci_mem_start; > + avail.end = pci_mem_start + pci_mem_gap_size - 1; > + avail.flags = IORESOURCE_MEM | IORESOURCE_WINDOW; > + avail.name = ci->name; > + clip_resource_from_mmcfg(&avail); > + if (avail.end > avail.start) { > + rentry = resource_list_create_entry(NULL, 0); > + if (rentry) { > + *rentry->res = avail; > + resource_list_add_tail(rentry, &ci->resources); > + } > + } > + } > + > return status; > } > > diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c > index de6bf0e7e8f8..1f3ffb1bcdc8 100644 > --- a/arch/x86/pci/mmconfig-shared.c > +++ b/arch/x86/pci/mmconfig-shared.c > @@ -813,3 +813,31 @@ int pci_mmconfig_delete(u16 seg, u8 start, u8 end) > > return -ENOENT; > } > + > +void pci_mmconfig_clip_resource(struct resource *res) > +{ > + struct pci_mmcfg_region *cfg; > + resource_size_t start, end; > + resource_size_t low = 0, high = 0; > + > + /* Refers to the resource_clip() in the x86/kernel/resource.c */ > + list_for_each_entry_rcu(cfg, &pci_mmcfg_list, list) { > + start = cfg->res.start; > + end = cfg->res.end; > + > + if (res->end < start || res->start > end) > + continue; /* no conflict */ > + > + if (res->start < start) > + low = start - res->start; > + > + if (res->end > end) > + high = res->end - end; > + > + /* Keep the area above or below the conflict, whichever is larger */ > + if (low > high) > + res->end = start - 1; > + else > + res->start = end + 1; > + } > +} > -- > 2.25.1 >
On 10/7/21 4:58 AM, Bjorn Helgaas wrote: > [+cc Myron, just FYI] > > On Thu, Jun 24, 2021 at 05:53:24PM +0800, Hui Wang wrote: >> The touchpad can't work on many Lenovo Ideapad S145/BS145 laptops. >> But it works well under Windows. >> >> On those machines, the touchpad is an I2C device, while the I2C host >> controllers fail to initialize as below shown: >> pci 0000:00:15.0: BAR 0: no space for [mem size 0x00001000 64bit] >> pci 0000:00:15.0: BAR 0: failed to assign [mem size 0x00001000 64bit] >> pci 0000:00:15.1: BAR 0: no space for [mem size 0x00001000 64bit] >> pci 0000:00:15.1: BAR 0: failed to assign [mem size 0x00001000 64bit] >> >> The BIOS assigns iomem space to host bridge and I2C host controller >> like this: >> pci_bus 0000:00: root bus resource [mem 0x000a0000-0x000bffff window] >> pci_bus 0000:00: root bus resource [mem 0x65400000-0xbfffffff window] >> >> pci 0000:00:15.0: [8086:34e8] type 00 class 0x0c8000 >> pci 0000:00:15.0: reg 0x10: [mem 0x00000000-0x00000fff 64bit] >> pci 0000:00:15.1: [8086:34e9] type 00 class 0x0c8000 >> pci 0000:00:15.1: reg 0x10: [mem 0x00000000-0x00000fff 64bit] >> >> The I2C host controllers need to allocate iomem space from root >> bridge, but all iomem window of the root bridge are overlapped with >> BIOS-e820 mapped region, that makes the allocate_resource() fail: >> BIOS-e820: [mem 0x0000000000000000-0x000000000009efff] usable >> BIOS-e820: [mem 0x000000000009f000-0x00000000000fffff] reserved >> ... >> BIOS-e820: [mem 0x000000004bc50000-0x00000000cfffffff] reserved >> >> We could add "pci=nocrs" to make the touchpad work, but users expect >> the touchpad to work out-of-box under Linux distro as under Windows. >> >> Here design a generic solution for x86 machines, if host bridge uses >> crs, we will check if all root bridge iomem windows are overlapped >> with BIOS-e820 mapped region, if yes, we try to build a non-e820 >> mapped window according to the biggest gap in the e820 mapped region, >> and we need to clip this window with MMCONFIG region if this region >> is not mapped by BIOS-e820, then insert this window to the tail of >> the root bridge. >> >> After this change, the I2C host controller could allocate the iomem >> region from host bridge successfully and the touchpad could work >> out-of-box. > I see from > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1931715 that a > fix has been committed, I assume to the Ubuntu kernel, but I assume > this is still a problem for upstream and probably other distro > kernels. No, the patch is not applied to Ubuntu kernels, Someone set it to committed by a mistake, and the bug status was changed back to confirmed already. > The 0-day bot found some issue, which I haven't looked at: > https://lore.kernel.org/r/20210627143859.GD17986@xsang-OptiPlex-9020 I reread the dmesg today, found all pci root bridges have at least one iomem window which is not overlapped with e820 reserved region, that is to say, in theory my patch will not assign new iomem window for any pci root bridges. So I don't know how my patch introduces the crashing on that machine. > I think this patch might be the wrong approach. We learned from _CRS > that [mem 0x65400000-0xbfffffff window] is assigned to the PNP0A08:00 > host bridge. > > The e820 "[mem 0x000000004bc50000-0x00000000cfffffff] reserved" region > certainly includes all of that PCI aperture, and this entry should > prevent that space from being allocated to devices that haven't > already been assigned space. > > But I don't think that e820 entry should prevent the PCI core from > managing that PCI aperture. The platform told us that PNP0A08:00 owns > the [mem 0x65400000-0xbfffffff window], and the PNP0A08:00 driver > (pci_root.c) should be able to manage it as needed. The e820 entry prevent the pci devices from getting the overlapped region by the path below: kernel/resource.c:__find_resource()--->arch/x86/kernel/resource.c:arch_remove_reservations()--->remove_e820_regions() Maybe we could remove arch_remove_reservations() as other architectures? Regards, Hui. > >> BugLink: http://bugs.launchpad.net/bugs/1931715 >> BugLink: http://bugs.launchpad.net/bugs/1932069 >> BugLink: http://bugs.launchpad.net/bugs/1921649 >> Cc: Bjorn Helgaas <bhelgaas@google.com> >> Cc: Yinghai Lu <yinghai@kernel.org> >> Cc: Ingo Molnar <mingo@redhat.com> >> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> >> Cc: linux-acpi@vger.kernel.org >> Cc: linux-pci@vger.kernel.org >> Signed-off-by: Hui Wang <hui.wang@canonical.com> >> --- >> arch/x86/include/asm/e820/api.h | 1 + >> arch/x86/include/asm/pci.h | 2 ++ >> arch/x86/include/asm/pci_x86.h | 1 + >> arch/x86/kernel/e820.c | 2 ++ >> arch/x86/pci/acpi.c | 46 ++++++++++++++++++++++++++++++++- >> arch/x86/pci/mmconfig-shared.c | 28 ++++++++++++++++++++ >> 6 files changed, 79 insertions(+), 1 deletion(-) >>
diff --git a/arch/x86/include/asm/e820/api.h b/arch/x86/include/asm/e820/api.h index e8f58ddd06d9..46c76201dc28 100644 --- a/arch/x86/include/asm/e820/api.h +++ b/arch/x86/include/asm/e820/api.h @@ -9,6 +9,7 @@ extern struct e820_table *e820_table_kexec; extern struct e820_table *e820_table_firmware; extern unsigned long pci_mem_start; +extern unsigned long pci_mem_gap_size; extern bool e820__mapped_raw_any(u64 start, u64 end, enum e820_type type); extern bool e820__mapped_any(u64 start, u64 end, enum e820_type type); diff --git a/arch/x86/include/asm/pci.h b/arch/x86/include/asm/pci.h index d2c76c8d8cfd..a940a792ef7b 100644 --- a/arch/x86/include/asm/pci.h +++ b/arch/x86/include/asm/pci.h @@ -81,6 +81,8 @@ static inline int pcibios_assign_all_busses(void) { return 0; } #endif extern unsigned long pci_mem_start; +extern unsigned long pci_mem_gap_size; + #define PCIBIOS_MIN_IO 0x1000 #define PCIBIOS_MIN_MEM (pci_mem_start) diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h index 490411dba438..3ea30aed9100 100644 --- a/arch/x86/include/asm/pci_x86.h +++ b/arch/x86/include/asm/pci_x86.h @@ -171,6 +171,7 @@ extern int pci_mmconfig_delete(u16 seg, u8 start, u8 end); extern struct pci_mmcfg_region *pci_mmconfig_lookup(int segment, int bus); extern struct pci_mmcfg_region *__init pci_mmconfig_add(int segment, int start, int end, u64 addr); +extern void pci_mmconfig_clip_resource(struct resource *res); extern struct list_head pci_mmcfg_list; diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index bc0657f0deed..2933745b19b7 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -66,6 +66,7 @@ struct e820_table *e820_table_firmware __refdata = &e820_table_firmware_init; /* For PCI or other memory-mapped resources */ unsigned long pci_mem_start = 0xaeedbabe; +unsigned long pci_mem_gap_size; #ifdef CONFIG_PCI EXPORT_SYMBOL(pci_mem_start); #endif @@ -677,6 +678,7 @@ __init void e820__setup_pci_gap(void) * e820__reserve_resources_late() protects stolen RAM already: */ pci_mem_start = gapstart; + pci_mem_gap_size = gapsize; pr_info("[mem %#010lx-%#010lx] available for PCI devices\n", gapstart, gapstart + gapsize - 1); diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c index 948656069cdd..e3a691024683 100644 --- a/arch/x86/pci/acpi.c +++ b/arch/x86/pci/acpi.c @@ -231,6 +231,11 @@ static void teardown_mcfg_map(struct acpi_pci_root_info *ci) info->mcfg_added = false; } } + +static void clip_resource_from_mmcfg(struct resource *res) +{ + return pci_mmconfig_clip_resource(res); +} #else static int setup_mcfg_map(struct acpi_pci_root_info *ci) { @@ -240,6 +245,10 @@ static int setup_mcfg_map(struct acpi_pci_root_info *ci) static void teardown_mcfg_map(struct acpi_pci_root_info *ci) { } + +static void clip_resource_from_mmcfg(struct resource *res) +{ +} #endif static int pci_acpi_root_get_node(struct acpi_pci_root *root) @@ -296,13 +305,48 @@ static int pci_acpi_root_prepare_resources(struct acpi_pci_root_info *ci) struct acpi_device *device = ci->bridge; int busnum = ci->root->secondary.start; struct resource_entry *entry, *tmp; + bool has_non_e820_region = false; int status; status = acpi_pci_probe_root_resources(ci); if (pci_use_crs) { - resource_list_for_each_entry_safe(entry, tmp, &ci->resources) + resource_list_for_each_entry_safe(entry, tmp, &ci->resources) { + struct resource avail = *entry->res; + if (resource_is_pcicfg_ioport(entry->res)) resource_list_destroy_entry(entry); + + if (avail.flags & IORESOURCE_MEM) { + arch_remove_reservations(&avail); + if (avail.end > avail.start) + has_non_e820_region = true; + } + } + + /* all bridge windows are in the BIOS-e820 mapped region, this + * will make allocate_resource() fail when PCI devices request + * iomem address from bridge. To fix it, we try to build a non + * e820 mapped iomem resource and clip it with MMCONFIG region, + * then add it to the bridge window list. + */ + if (!has_non_e820_region) { + struct resource_entry *rentry; + struct resource avail; + + avail.start = pci_mem_start; + avail.end = pci_mem_start + pci_mem_gap_size - 1; + avail.flags = IORESOURCE_MEM | IORESOURCE_WINDOW; + avail.name = ci->name; + clip_resource_from_mmcfg(&avail); + if (avail.end > avail.start) { + rentry = resource_list_create_entry(NULL, 0); + if (rentry) { + *rentry->res = avail; + resource_list_add_tail(rentry, &ci->resources); + } + } + } + return status; } diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c index de6bf0e7e8f8..1f3ffb1bcdc8 100644 --- a/arch/x86/pci/mmconfig-shared.c +++ b/arch/x86/pci/mmconfig-shared.c @@ -813,3 +813,31 @@ int pci_mmconfig_delete(u16 seg, u8 start, u8 end) return -ENOENT; } + +void pci_mmconfig_clip_resource(struct resource *res) +{ + struct pci_mmcfg_region *cfg; + resource_size_t start, end; + resource_size_t low = 0, high = 0; + + /* Refers to the resource_clip() in the x86/kernel/resource.c */ + list_for_each_entry_rcu(cfg, &pci_mmcfg_list, list) { + start = cfg->res.start; + end = cfg->res.end; + + if (res->end < start || res->start > end) + continue; /* no conflict */ + + if (res->start < start) + low = start - res->start; + + if (res->end > end) + high = res->end - end; + + /* Keep the area above or below the conflict, whichever is larger */ + if (low > high) + res->end = start - 1; + else + res->start = end + 1; + } +}
The touchpad can't work on many Lenovo Ideapad S145/BS145 laptops. But it works well under Windows. On those machines, the touchpad is an I2C device, while the I2C host controllers fail to initialize as below shown: pci 0000:00:15.0: BAR 0: no space for [mem size 0x00001000 64bit] pci 0000:00:15.0: BAR 0: failed to assign [mem size 0x00001000 64bit] pci 0000:00:15.1: BAR 0: no space for [mem size 0x00001000 64bit] pci 0000:00:15.1: BAR 0: failed to assign [mem size 0x00001000 64bit] The BIOS assigns iomem space to host bridge and I2C host controller like this: pci_bus 0000:00: root bus resource [mem 0x000a0000-0x000bffff window] pci_bus 0000:00: root bus resource [mem 0x65400000-0xbfffffff window] pci 0000:00:15.0: [8086:34e8] type 00 class 0x0c8000 pci 0000:00:15.0: reg 0x10: [mem 0x00000000-0x00000fff 64bit] pci 0000:00:15.1: [8086:34e9] type 00 class 0x0c8000 pci 0000:00:15.1: reg 0x10: [mem 0x00000000-0x00000fff 64bit] The I2C host controllers need to allocate iomem space from root bridge, but all iomem window of the root bridge are overlapped with BIOS-e820 mapped region, that makes the allocate_resource() fail: BIOS-e820: [mem 0x0000000000000000-0x000000000009efff] usable BIOS-e820: [mem 0x000000000009f000-0x00000000000fffff] reserved ... BIOS-e820: [mem 0x000000004bc50000-0x00000000cfffffff] reserved We could add "pci=nocrs" to make the touchpad work, but users expect the touchpad to work out-of-box under Linux distro as under Windows. Here design a generic solution for x86 machines, if host bridge uses crs, we will check if all root bridge iomem windows are overlapped with BIOS-e820 mapped region, if yes, we try to build a non-e820 mapped window according to the biggest gap in the e820 mapped region, and we need to clip this window with MMCONFIG region if this region is not mapped by BIOS-e820, then insert this window to the tail of the root bridge. After this change, the I2C host controller could allocate the iomem region from host bridge successfully and the touchpad could work out-of-box. BugLink: http://bugs.launchpad.net/bugs/1931715 BugLink: http://bugs.launchpad.net/bugs/1932069 BugLink: http://bugs.launchpad.net/bugs/1921649 Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: linux-acpi@vger.kernel.org Cc: linux-pci@vger.kernel.org Signed-off-by: Hui Wang <hui.wang@canonical.com> --- arch/x86/include/asm/e820/api.h | 1 + arch/x86/include/asm/pci.h | 2 ++ arch/x86/include/asm/pci_x86.h | 1 + arch/x86/kernel/e820.c | 2 ++ arch/x86/pci/acpi.c | 46 ++++++++++++++++++++++++++++++++- arch/x86/pci/mmconfig-shared.c | 28 ++++++++++++++++++++ 6 files changed, 79 insertions(+), 1 deletion(-)