Commit dfb5c1e1 authored by Wei Liu's avatar Wei Liu
Browse files

x86/hyperv: remove on-stack cpumask from hv_send_ipi_mask_allbutself 



It is not a good practice to allocate a cpumask on stack, given it may
consume up to 1 kilobytes of stack space if the kernel is configured to
have 8192 cpus.

The internal helper functions __send_ipi_mask{,_ex} need to loop over
the provided mask anyway, so it is not too difficult to skip `self'
there. We can thus do away with the on-stack cpumask in
hv_send_ipi_mask_allbutself.

Adjust call sites of __send_ipi_mask as needed.

Reported-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Suggested-by: default avatarMichael Kelley <mikelley@microsoft.com>
Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Fixes: 68bb7bfb ("X86/Hyper-V: Enable IPI enlightenments")
Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20210910185714.299411-3-wei.liu@kernel.org
parent 7ad9bb9d

arch/x86/hyperv/hv_apic.c

+26 −17
Original line number Diff line number Diff line
@@ -99,7 +99,8 @@ static void hv_apic_eoi_write(u32 reg, u32 val) 
/*

 * IPI implementation on Hyper-V.

 */

static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector)

static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector,

		bool exclude_self)

{

	struct hv_send_ipi_ex **arg;

	struct hv_send_ipi_ex *ipi_arg;
@@ -123,6 +124,9 @@ static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector) 


	if (!cpumask_equal(mask, cpu_present_mask)) {

		ipi_arg->vp_set.format = HV_GENERIC_SET_SPARSE_4K;

		if (exclude_self)

			nr_bank = cpumask_to_vpset_noself(&(ipi_arg->vp_set), mask);

		else

			nr_bank = cpumask_to_vpset(&(ipi_arg->vp_set), mask);

	}

	if (nr_bank < 0)
@@ -138,15 +142,25 @@ static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector) 
	return hv_result_success(status);

}



static bool __send_ipi_mask(const struct cpumask *mask, int vector)

static bool __send_ipi_mask(const struct cpumask *mask, int vector,

		bool exclude_self)

{

	int cur_cpu, vcpu;

	int cur_cpu, vcpu, this_cpu = smp_processor_id();

	struct hv_send_ipi ipi_arg;

	u64 status;

	unsigned int weight;



	trace_hyperv_send_ipi_mask(mask, vector);



	if (cpumask_empty(mask))

	weight = cpumask_weight(mask);



	/*

	 * Do nothing if

	 *   1. the mask is empty

	 *   2. the mask only contains self when exclude_self is true

	 */

	if (weight == 0 ||

	    (exclude_self && weight == 1 && cpumask_test_cpu(this_cpu, mask)))

		return true;



	if (!hv_hypercall_pg)
@@ -172,6 +186,8 @@ static bool __send_ipi_mask(const struct cpumask *mask, int vector) 
	ipi_arg.cpu_mask = 0;



	for_each_cpu(cur_cpu, mask) {

		if (exclude_self && cur_cpu == this_cpu)

			continue;

		vcpu = hv_cpu_number_to_vp_number(cur_cpu);

		if (vcpu == VP_INVAL)

			return false;
@@ -191,7 +207,7 @@ static bool __send_ipi_mask(const struct cpumask *mask, int vector) 
	return hv_result_success(status);



do_ex_hypercall:

	return __send_ipi_mask_ex(mask, vector);

	return __send_ipi_mask_ex(mask, vector, exclude_self);

}



static bool __send_ipi_one(int cpu, int vector)
@@ -208,7 +224,7 @@ static bool __send_ipi_one(int cpu, int vector) 
		return false;



	if (vp >= 64)

		return __send_ipi_mask_ex(cpumask_of(cpu), vector);

		return __send_ipi_mask_ex(cpumask_of(cpu), vector, false);



	status = hv_do_fast_hypercall16(HVCALL_SEND_IPI, vector, BIT_ULL(vp));

	return hv_result_success(status);
@@ -222,20 +238,13 @@ static void hv_send_ipi(int cpu, int vector) 


static void hv_send_ipi_mask(const struct cpumask *mask, int vector)

{

	if (!__send_ipi_mask(mask, vector))

	if (!__send_ipi_mask(mask, vector, false))

		orig_apic.send_IPI_mask(mask, vector);

}



static void hv_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)

{

	unsigned int this_cpu = smp_processor_id();

	struct cpumask new_mask;

	const struct cpumask *local_mask;



	cpumask_copy(&new_mask, mask);

	cpumask_clear_cpu(this_cpu, &new_mask);

	local_mask = &new_mask;

	if (!__send_ipi_mask(local_mask, vector))

	if (!__send_ipi_mask(mask, vector, true))

		orig_apic.send_IPI_mask_allbutself(mask, vector);

}
@@ -246,7 +255,7 @@ static void hv_send_ipi_allbutself(int vector) 


static void hv_send_ipi_all(int vector)

{

	if (!__send_ipi_mask(cpu_online_mask, vector))

	if (!__send_ipi_mask(cpu_online_mask, vector, false))

		orig_apic.send_IPI_all(vector);

}