linux-kernel - [PATCH v2 1/2] asm-generic/hyperv: provide cpumask_to_vpset

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Date:   Fri, 10 Sep 2021 18:57:13 +0000
From:   Wei Liu <wei.liu@...nel.org>
To:     Linux on Hyper-V List <linux-hyperv@...r.kernel.org>
Cc:     Michael Kelley <mikelley@...rosoft.com>, kys@...rosoft.com,
        haiyangz@...rosoft.com, decui@...rosoft.com,
        sthemmin@...rosoft.com, Wei Liu <wei.liu@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        linux-arch@...r.kernel.org (open list:GENERIC INCLUDE/ASM HEADER FILES),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v2 1/2] asm-generic/hyperv: provide cpumask_to_vpset_noself

This is a new variant which removes `self' cpu from the vpset. It will
be used in Hyper-V enlightened IPI code.

Signed-off-by: Wei Liu <wei.liu@...nel.org>
---
Provide a new variant instead of adding a new parameter because it makes
it easier to backport -- we don't need to fix the users of
cpumask_to_vpset.

v2:
1. Rename function
2. Add preemptible check
---
 include/asm-generic/mshyperv.h | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index 9a000ba2bb75..9a134806f1d5 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -184,10 +184,12 @@ static inline int hv_cpu_number_to_vp_number(int cpu_number)
 	return hv_vp_index[cpu_number];
 }
 
-static inline int cpumask_to_vpset(struct hv_vpset *vpset,
-				    const struct cpumask *cpus)
+static inline int __cpumask_to_vpset(struct hv_vpset *vpset,
+				    const struct cpumask *cpus,
+				    bool exclude_self)
 {
 	int cpu, vcpu, vcpu_bank, vcpu_offset, nr_bank = 1;
+	int this_cpu = smp_processor_id();
 
 	/* valid_bank_mask can represent up to 64 banks */
 	if (hv_max_vp_index / 64 >= 64)
@@ -205,6 +207,8 @@ static inline int cpumask_to_vpset(struct hv_vpset *vpset,
 	 * Some banks may end up being empty but this is acceptable.
 	 */
 	for_each_cpu(cpu, cpus) {
+		if (exclude_self && cpu == this_cpu)
+			continue;
 		vcpu = hv_cpu_number_to_vp_number(cpu);
 		if (vcpu == VP_INVAL)
 			return -1;
@@ -219,6 +223,19 @@ static inline int cpumask_to_vpset(struct hv_vpset *vpset,
 	return nr_bank;
 }
 
+static inline int cpumask_to_vpset(struct hv_vpset *vpset,
+				    const struct cpumask *cpus)
+{
+	return __cpumask_to_vpset(vpset, cpus, false);
+}
+
+static inline int cpumask_to_vpset_noself(struct hv_vpset *vpset,
+				    const struct cpumask *cpus)
+{
+	WARN_ON_ONCE(preemptible());
+	return __cpumask_to_vpset(vpset, cpus, true);
+}
+
 void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die);
 bool hv_is_hyperv_initialized(void);
 bool hv_is_hibernation_supported(void);
-- 
2.30.2