From 8abc3122aa02567bfe626cd13f4d34853c9b1225 Mon Sep 17 00:00:00 2001 From: Robert Richter Date: Tue, 27 Mar 2012 20:04:02 +0200 Subject: [PATCH] x86/apic/amd: Be more verbose about LVT offset assignments Add information about LVT offset assignments to better debug firmware bugs related to this. See following examples. # dmesg | grep -i 'offset\|ibs' LVT offset 0 assigned for vector 0xf9 [Firmware Bug]: cpu 0, try to use APIC500 (LVT offset 0) for vector 0x10400, but the register is already in use for vector 0xf9 on another cpu [Firmware Bug]: cpu 0, IBS interrupt offset 0 not available (MSRC001103A=0x0000000000000100) Failed to setup IBS, -22 In this case the BIOS assigns both offsets for MCE (0xf9) and IBS (0x400) vectors to offset 0, which is why the second APIC setup (IBS) failed. With correct setup you get: # dmesg | grep -i 'offset\|ibs' LVT offset 0 assigned for vector 0xf9 LVT offset 1 assigned for vector 0x400 IBS: LVT offset 1 assigned perf: AMD IBS detected (0x00000007) oprofile: AMD IBS detected (0x00000007) Note: The vector includes also the message type to handle also NMIs (0x400). In the firmware bug message the format is the same as of the APIC500 register and includes the mask bit (bit 16) in addition. Signed-off-by: Robert Richter Signed-off-by: Ingo Molnar --- arch/x86/kernel/apic/apic.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index 2eec05b6d1b8..11544d8f1e97 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -383,20 +383,25 @@ static inline int eilvt_entry_is_changeable(unsigned int old, unsigned int new) static unsigned int reserve_eilvt_offset(int offset, unsigned int new) { - unsigned int rsvd; /* 0: uninitialized */ + unsigned int rsvd, vector; if (offset >= APIC_EILVT_NR_MAX) return ~0; - rsvd = atomic_read(&eilvt_offsets[offset]) & ~APIC_EILVT_MASKED; + rsvd = atomic_read(&eilvt_offsets[offset]); do { - if (rsvd && - !eilvt_entry_is_changeable(rsvd, new)) + vector = rsvd & ~APIC_EILVT_MASKED; /* 0: unassigned */ + if (vector && !eilvt_entry_is_changeable(vector, new)) /* may not change if vectors are different */ return rsvd; rsvd = atomic_cmpxchg(&eilvt_offsets[offset], rsvd, new); } while (rsvd != new); + rsvd &= ~APIC_EILVT_MASKED; + if (rsvd && rsvd != vector) + pr_info("LVT offset %d assigned for vector 0x%02x\n", + offset, rsvd); + return new; } -- 2.30.2