From 7f284d3cc96e02468a42e045f77af11e5ff8b095 Mon Sep 17 00:00:00 2001 From: Frank Arnold Date: Thu, 22 Apr 2010 16:06:59 +0200 Subject: x86, cacheinfo: Turn off L3 cache index disable feature in virtualized environments When running a quest kernel on xen we get: BUG: unable to handle kernel NULL pointer dereference at 0000000000000038 IP: [] cpuid4_cache_lookup_regs+0x2ca/0x3df PGD 0 Oops: 0000 [#1] SMP last sysfs file: CPU 0 Modules linked in: Pid: 0, comm: swapper Tainted: G W 2.6.34-rc3 #1 /HVM domU RIP: 0010:[] [] cpuid4_cache_lookup_regs+0x 2ca/0x3df RSP: 0018:ffff880002203e08 EFLAGS: 00010046 RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000060 RDX: 0000000000000000 RSI: 0000000000000040 RDI: 0000000000000000 RBP: ffff880002203ed8 R08: 00000000000017c0 R09: ffff880002203e38 R10: ffff8800023d5d40 R11: ffffffff81a01e28 R12: ffff880187e6f5c0 R13: ffff880002203e34 R14: ffff880002203e58 R15: ffff880002203e68 FS: 0000000000000000(0000) GS:ffff880002200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000038 CR3: 0000000001a3c000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process swapper (pid: 0, threadinfo ffffffff81a00000, task ffffffff81a44020) Stack: ffffffff810d7ecb ffff880002203e20 ffffffff81059140 ffff880002203e30 <0> ffffffff810d7ec9 0000000002203e40 000000000050d140 ffff880002203e70 <0> 0000000002008140 0000000000000086 ffff880040020140 ffffffff81068b8b Call Trace: [] ? sync_supers_timer_fn+0x0/0x1c [] ? mod_timer+0x23/0x25 [] ? arm_supers_timer+0x34/0x36 [] ? hrtimer_get_next_event+0xa7/0xc3 [] ? get_next_timer_interrupt+0x19a/0x20d [] get_cpu_leaves+0x5c/0x232 [] ? sched_clock_local+0x1c/0x82 [] ? sched_clock_tick+0x75/0x7a [] generic_smp_call_function_single_interrupt+0xae/0xd0 [] smp_call_function_single_interrupt+0x18/0x27 [] call_function_single_interrupt+0x13/0x20 [] ? notifier_call_chain+0x14/0x63 [] ? native_safe_halt+0xc/0xd [] ? default_idle+0x36/0x53 [] cpu_idle+0xaa/0xe4 [] rest_init+0x7e/0x80 [] start_kernel+0x40e/0x419 [] x86_64_start_reservations+0xb3/0xb7 [] x86_64_start_kernel+0xf8/0x107 Code: 14 d5 40 ff ae 81 8b 14 02 31 c0 3b 15 47 1c 8b 00 7d 0e 48 8b 05 36 1c 8b 00 48 63 d2 48 8b 04 d0 c7 85 5c ff ff ff 00 00 00 00 <8b> 70 38 48 8d 8d 5c ff ff ff 48 8b 78 10 ba c4 01 00 00 e8 eb RIP [] cpuid4_cache_lookup_regs+0x2ca/0x3df RSP CR2: 0000000000000038 ---[ end trace a7919e7f17c0a726 ]--- The L3 cache index disable feature of AMD CPUs has to be disabled if the kernel is running as guest on top of a hypervisor because northbridge devices are not available to the guest. Currently, this fixes a boot crash on top of Xen. In the future this will become an issue on KVM as well. Check if northbridge devices are present and do not enable the feature if there are none. [ hpa: backported to 2.6.34 ] Signed-off-by: Frank Arnold LKML-Reference: <1271945222-5283-3-git-send-email-bp@amd64.org> Acked-by: Borislav Petkov Signed-off-by: H. Peter Anvin Cc: --- arch/x86/kernel/cpu/intel_cacheinfo.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c index b3eeb66c0a51..95962a93f99a 100644 --- a/arch/x86/kernel/cpu/intel_cacheinfo.c +++ b/arch/x86/kernel/cpu/intel_cacheinfo.c @@ -340,6 +340,10 @@ amd_check_l3_disable(int index, struct _cpuid4_info_regs *this_leaf) (boot_cpu_data.x86_mask < 0x1))) return; + /* not in virtualized environments */ + if (num_k8_northbridges == 0) + return; + this_leaf->can_disable = true; this_leaf->l3_indices = amd_calc_l3_indices(); } -- cgit v1.2.3-58-ga151