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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: Linus Torvalds <torvalds@linux-foundation.org>
Suggested-by: Michael Kelley <mikelley@microsoft.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes: 68bb7bfb79 ("X86/Hyper-V: Enable IPI enlightenments")
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20210910185714.299411-3-wei.liu@kernel.org
This commit is contained in:
Wei Liu 2021-09-10 18:57:14 +00:00
parent 7ad9bb9d0f
commit dfb5c1e12c
1 changed files with 26 additions and 17 deletions
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43
arch/x86/hyperv/hv_apic.c
View File

@ -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;
@ -123,7 +124,10 @@ 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;
nr_bank = cpumask_to_vpset(&(ipi_arg->vp_set), mask);
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)
goto ipi_mask_ex_done;
@ -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);
}