Messages in this thread Patch in this message | | | From | Andrew Banman <> | Subject | [PATCH] x86/platform/uv/BAU: gracefully disable BAU during panic | Date | Mon, 13 Aug 2018 08:54:37 -0500 |
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When we panic while the BAU is active, outstanding broadcasts may go un-acknowledged by the kernel. These broadcasts cause timeouts in the UV ASIC that tie up BAU resources, which may cause a fatal error that brings down the system, thereby crashing the kdump kexec.
Add uv_bau_crash_shutdown() to bring BAU to quiescence ahead of the crash shutdown routine saved in smp machine_ops. Assign uv_bau_crash_shutdown to machine_ops during init.
Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Colin Ian King <colin.king@canonical.com> Cc: Dimitri Sivanich <sivanich@hpe.com> Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org Acked-by: Mike Travis <mike.travis@hpe.com> Signed-off-by: Andrew Banman <abanman@hpe.com> --- arch/x86/platform/uv/tlb_uv.c | 49 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+)
diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c index e26dfad..dae6b3c 100644 --- a/arch/x86/platform/uv/tlb_uv.c +++ b/arch/x86/platform/uv/tlb_uv.c @@ -22,8 +22,13 @@ #include <asm/tsc.h> #include <asm/irq_vectors.h> #include <asm/timer.h> +#include <asm/reboot.h> static struct bau_operations ops __ro_after_init; +#ifdef CONFIG_KEXEC_CORE +static void (*crash_shutdown)(struct pt_regs *regs) __ro_after_init; +static bool crash_in_progress; +#endif /* timeouts in nanoseconds (indexed by UVH_AGING_PRESCALE_SEL urgency7 30:28) */ static const int timeout_base_ns[] = { @@ -2195,6 +2200,44 @@ static int __init init_per_cpu(int nuvhubs, int base_part_pnode) .wait_completion = uv4_wait_completion, }; +#ifdef CONFIG_KEXEC_CORE +/* + * Bring BAU to quiesence by abandoning current broadcasts and freeing up + * resources needed by firmware-initiated BAU broadcasts. + */ +void uv_bau_crash_shutdown(struct pt_regs *regs) +{ + int pnode = 0; + int uvhub = 0; + + if (crash_in_progress) + return; + crash_in_progress = true; + + /* + * Don't bother turning off BAU in the per-cpu structs. We free up + * enough INTD resources to accommodate any new broadcasts that + * may (however unlikley) start up before we complete the panic, + * without tying up FW-initiated General Broadcasts that must not + * time out. + */ + + for_each_possible_blade(uvhub) { + if (!uv_blade_nr_possible_cpus(uvhub)) + continue; + pnode = uv_blade_to_pnode(uvhub); + /* Set STATUS registers to idle to free source cpus */ + write_gmmr(pnode, UVH_LB_BAU_SB_ACTIVATION_STATUS_0, 0x0); + write_gmmr(pnode, UVH_LB_BAU_SB_ACTIVATION_STATUS_1, 0x0); + write_gmmr(pnode, UVH_LB_BAU_SB_ACTIVATION_STATUS_2, 0x0); + /* Clear TIMEOUT and PENDING bits to free up BAU resources */ + ops.write_g_sw_ack(pnode, ops.read_g_sw_ack(pnode) & 0xFFFF); + } + + crash_shutdown(regs); +} +#endif + /* * Initialization of BAU-related structures */ @@ -2267,6 +2310,12 @@ static int __init uv_bau_init(void) } } +#ifdef CONFIG_KEXEC_CORE + crash_shutdown = machine_ops.crash_shutdown; + machine_ops.crash_shutdown = uv_bau_crash_shutdown; + crash_in_progress = false; +#endif + return 0; err_bau_disable: -- 1.8.2.1
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