Commit 4bd06060 authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Thomas Gleixner
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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: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
Cc: devel@linuxdriverproject.org
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Tianyu Lan <Tianyu.Lan@microsoft.com>
Cc: "Michael Kelley (EOSG)" <Michael.H.Kelley@microsoft.com>
Link: https://lkml.kernel.org/r/20180622170625.30688-4-vkuznets@redhat.com
parent d8e6b232

arch/x86/hyperv/hv_apic.c

+20 −9
Original line number Diff line number Diff line
@@ -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)
@@ -218,9 +232,6 @@ 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");

		/*

		 * Set the IPI entry points.

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