Felix Held has submitted this change. ( https://review.coreboot.org/c/coreboot/+/80330?usp=email )
Change subject: arch/x86/ioapic: always write IOAPIC ID in set_ioapic_id ......................................................................
arch/x86/ioapic: always write IOAPIC ID in set_ioapic_id
Back in the days of the APIC bus, the IOAPIC IDs mustn't overlap with the LAPIC IDs (0 to CONFIG_MAX_CPUS - 1), but since the IOAPIC and LAPIC nowadays talk to each other via the system bus, an IOAPIC ID of 0 is valid. When set_ioapic_id gets called with an IOAPIC ID of 0, it skipped writing the IOAPIC ID to the corresponding IOAPIC register, so the code was relying of the register having the expected default value of the IOAPIC IO 0 for things to work as expected. The case of the IOAPIC ID being 0 is the most common case in coreboot, since that's what register_new_ioapic_gsi0 will end up doing. Fix this issue by not making the io_apic_write call conditional on ioapic_id being non-zero. The only southbridge that doesn't call register_new_ioapic_gsi0, calls set_ioapic_id with the IOAPIC ID 2 for which this won't cause any changes in behavior.
Signed-off-by: Felix Held felix-coreboot@felixheld.de Change-Id: Ic8538f82a6b10f16eeb228669db197dc8e326ffd Reviewed-on: https://review.coreboot.org/c/coreboot/+/80330 Tested-by: build bot (Jenkins) no-reply@coreboot.org Reviewed-by: Nico Huber nico.h@gmx.de Reviewed-by: Matt DeVillier matt.devillier@amd.corp-partner.google.com Reviewed-by: Arthur Heymans arthur@aheymans.xyz --- M src/arch/x86/ioapic.c 1 file changed, 2 insertions(+), 6 deletions(-)
Approvals: Matt DeVillier: Looks good to me, approved build bot (Jenkins): Verified Arthur Heymans: Looks good to me, approved Nico Huber: Looks good to me, but someone else must approve
diff --git a/src/arch/x86/ioapic.c b/src/arch/x86/ioapic.c index 04c852b..df97a50 100644 --- a/src/arch/x86/ioapic.c +++ b/src/arch/x86/ioapic.c @@ -131,12 +131,8 @@ ioapic_base); printk(BIOS_DEBUG, "IOAPIC: ID = 0x%02x\n", ioapic_id);
- if (ioapic_id) { - /* Set IOAPIC ID if it has been specified. */ - io_apic_write(ioapic_base, 0x00, - (io_apic_read(ioapic_base, 0x00) & 0xf0ffffff) | - (ioapic_id << 24)); - } + io_apic_write(ioapic_base, 0x00, + (io_apic_read(ioapic_base, 0x00) & 0xf0ffffff) | (ioapic_id << 24));
printk(BIOS_SPEW, "IOAPIC: Dumping registers\n"); for (i = 0; i < 3; i++)