From 4bd06060762bc7e4834ecf9daeb78834f7a29582 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Fri, 22 Jun 2018 19:06:24 +0200 Subject: [PATCH] x86/hyper-v: Use cheaper HVCALL_SEND_IPI hypercall when possible When there is no need to send an IPI to a CPU with VP number > 64 we can do the job with fast HVCALL_SEND_IPI hypercall. Signed-off-by: Vitaly Kuznetsov Signed-off-by: Thomas Gleixner Reviewed-by: Michael Kelley Cc: devel@linuxdriverproject.org Cc: "K. Y. Srinivasan" Cc: Haiyang Zhang Cc: Stephen Hemminger Cc: "H. Peter Anvin" Cc: Tianyu Lan Cc: "Michael Kelley (EOSG)" Link: https://lkml.kernel.org/r/20180622170625.30688-4-vkuznets@redhat.com --- arch/x86/hyperv/hv_apic.c | 29 ++++++++++++++++++++--------- 1 file changed, 20 insertions(+), 9 deletions(-) diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c index 90055f89223b..ee962784d25b 100644 --- a/arch/x86/hyperv/hv_apic.c +++ b/arch/x86/hyperv/hv_apic.c @@ -99,6 +99,9 @@ static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector) int nr_bank = 0; int ret = 1; + if (!(ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED)) + return false; + local_irq_save(flags); arg = (struct ipi_arg_ex **)this_cpu_ptr(hyperv_pcpu_input_arg); @@ -140,8 +143,18 @@ static bool __send_ipi_mask(const struct cpumask *mask, int vector) if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR)) return false; - if ((ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED)) - return __send_ipi_mask_ex(mask, vector); + /* + * From the supplied CPU set we need to figure out if we can get away + * with cheaper HVCALL_SEND_IPI hypercall. This is possible when the + * highest VP number in the set is < 64. As VP numbers are usually in + * ascending order and match Linux CPU ids, here is an optimization: + * we check the VP number for the highest bit in the supplied set first + * so we can quickly find out if using HVCALL_SEND_IPI_EX hypercall is + * a must. We will also check all VP numbers when walking the supplied + * CPU set to remain correct in all cases. + */ + if (hv_cpu_number_to_vp_number(cpumask_last(mask)) >= 64) + goto do_ex_hypercall; ipi_arg.vector = vector; ipi_arg.cpu_mask = 0; @@ -153,16 +166,17 @@ static bool __send_ipi_mask(const struct cpumask *mask, int vector) * only target upto 64 CPUs. */ if (vcpu >= 64) - goto ipi_mask_done; + goto do_ex_hypercall; __set_bit(vcpu, (unsigned long *)&ipi_arg.cpu_mask); } ret = hv_do_fast_hypercall16(HVCALL_SEND_IPI, ipi_arg.vector, ipi_arg.cpu_mask); - -ipi_mask_done: return ((ret == 0) ? true : false); + +do_ex_hypercall: + return __send_ipi_mask_ex(mask, vector); } static bool __send_ipi_one(int cpu, int vector) @@ -218,10 +232,7 @@ static void hv_send_ipi_self(int vector) void __init hv_apic_init(void) { if (ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) { - if ((ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED)) - pr_info("Hyper-V: Using ext hypercalls for IPI\n"); - else - pr_info("Hyper-V: Using IPI hypercalls\n"); + pr_info("Hyper-V: Using IPI hypercalls\n"); /* * Set the IPI entry points. */