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Subject[PATCH 2/5] X86: Hyper-V: Enable IPI enlightenments
Date
From: "K. Y. Srinivasan" <kys@microsoft.com>

Hyper-V supports hypercalls to implement IPI; use them.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
arch/x86/hyperv/hv_apic.c | 125 +++++++++++++++++++++++++++++++++++++
arch/x86/hyperv/hv_init.c | 17 +++++
arch/x86/include/asm/hyperv-tlfs.h | 9 +++
arch/x86/include/asm/mshyperv.h | 1 +
4 files changed, 152 insertions(+)

diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c
index e0a5b36208fc..7f3322ecfb01 100644
--- a/arch/x86/hyperv/hv_apic.c
+++ b/arch/x86/hyperv/hv_apic.c
@@ -30,6 +30,14 @@
#include <linux/slab.h>
#include <linux/cpuhotplug.h>

+struct ipi_arg_non_ex {
+ u32 vector;
+ u32 reserved;
+ u64 cpu_mask;
+};
+
+static struct apic orig_apic;
+
static u64 hv_apic_icr_read(void)
{
u64 reg_val;
@@ -85,8 +93,125 @@ static void hv_apic_eoi_write(u32 reg, u32 val)
wrmsr(HV_X64_MSR_EOI, val, 0);
}

+/*
+ * IPI implementation on Hyper-V.
+ */
+
+static int __send_ipi_mask(const struct cpumask *mask, int vector)
+{
+ int cur_cpu, vcpu;
+ struct ipi_arg_non_ex **arg;
+ struct ipi_arg_non_ex *ipi_arg;
+ int ret = 1;
+ unsigned long flags;
+
+ if (cpumask_empty(mask))
+ return 0;
+
+ if (!hv_hypercall_pg)
+ return ret;
+
+ if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR))
+ return ret;
+
+ local_irq_save(flags);
+ arg = (struct ipi_arg_non_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
+
+ ipi_arg = *arg;
+ if (unlikely(!ipi_arg))
+ goto ipi_mask_done;
+
+
+ ipi_arg->vector = vector;
+ ipi_arg->reserved = 0;
+ ipi_arg->cpu_mask = 0;
+
+ for_each_cpu(cur_cpu, mask) {
+ vcpu = hv_cpu_number_to_vp_number(cur_cpu);
+ if (vcpu >= 64)
+ goto ipi_mask_done;
+
+ __set_bit(vcpu, (unsigned long *)&ipi_arg->cpu_mask);
+ }
+
+ ret = hv_do_hypercall(HVCALL_SEND_IPI, ipi_arg, NULL);
+
+ipi_mask_done:
+ local_irq_restore(flags);
+ return ret;
+}
+
+static int __send_ipi_one(int cpu, int vector)
+{
+ struct cpumask mask = CPU_MASK_NONE;
+
+ cpumask_set_cpu(cpu, &mask);
+ return __send_ipi_mask(&mask, vector);
+}
+
+static void hv_send_ipi(int cpu, int vector)
+{
+ if (__send_ipi_one(cpu, vector))
+ orig_apic.send_IPI(cpu, vector);
+}
+
+static void hv_send_ipi_mask(const struct cpumask *mask, int vector)
+{
+ if (__send_ipi_mask(mask, vector))
+ 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))
+ orig_apic.send_IPI_mask_allbutself(mask, vector);
+}
+
+static void hv_send_ipi_allbutself(int vector)
+{
+ hv_send_ipi_mask_allbutself(cpu_online_mask, vector);
+}
+
+static void hv_send_ipi_all(int vector)
+{
+ if (__send_ipi_mask(cpu_online_mask, vector))
+ orig_apic.send_IPI_all(vector);
+}
+
+static void hv_send_ipi_self(int vector)
+{
+ if (__send_ipi_one(smp_processor_id(), vector))
+ orig_apic.send_IPI_self(vector);
+}
+
void __init hv_apic_init(void)
{
+ if (ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) {
+ if (hyperv_pcpu_input_arg == NULL)
+ goto msr_based_access;
+
+ pr_info("Hyper-V: Using IPI hypercalls\n");
+ /*
+ * Set the IPI entry points.
+ */
+ orig_apic = *apic;
+
+ apic->send_IPI = hv_send_ipi;
+ apic->send_IPI_mask = hv_send_ipi_mask;
+ apic->send_IPI_mask_allbutself = hv_send_ipi_mask_allbutself;
+ apic->send_IPI_allbutself = hv_send_ipi_allbutself;
+ apic->send_IPI_all = hv_send_ipi_all;
+ apic->send_IPI_self = hv_send_ipi_self;
+ }
+
+msr_based_access:
if (ms_hyperv.hints & HV_X64_APIC_ACCESS_RECOMMENDED) {
pr_info("Hyper-V: Using MSR ased APIC access\n");
apic_set_eoi_write(hv_apic_eoi_write);
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 71e50fc2b7ef..a895662b6b4c 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -91,12 +91,19 @@ EXPORT_SYMBOL_GPL(hv_vp_index);
struct hv_vp_assist_page **hv_vp_assist_page;
EXPORT_SYMBOL_GPL(hv_vp_assist_page);

+void __percpu **hyperv_pcpu_input_arg;
+EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
+
u32 hv_max_vp_index;

static int hv_cpu_init(unsigned int cpu)
{
u64 msr_vp_index;
struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
+ void **input_arg;
+
+ input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
+ *input_arg = page_address(alloc_page(GFP_ATOMIC));

hv_get_vp_index(msr_vp_index);

@@ -217,6 +224,10 @@ static int hv_cpu_die(unsigned int cpu)
{
struct hv_reenlightenment_control re_ctrl;
unsigned int new_cpu;
+ void **input_arg;
+
+ input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
+ free_page((unsigned long)*input_arg);

if (hv_vp_assist_page && hv_vp_assist_page[cpu])
wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
@@ -260,6 +271,12 @@ void __init hyperv_init(void)
if ((ms_hyperv.features & required_msrs) != required_msrs)
return;

+ /* Allocate the per-CPU state for the hypercall input arg */
+ hyperv_pcpu_input_arg = alloc_percpu(void *);
+
+ if (hyperv_pcpu_input_arg == NULL)
+ return;
+
/* Allocate percpu VP index */
hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
GFP_KERNEL);
diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index 416cb0e0c496..646cf2ca2aaa 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -164,6 +164,11 @@
*/
#define HV_X64_DEPRECATING_AEOI_RECOMMENDED (1 << 9)

+/*
+ * Recommend using cluster IPI hypercalls.
+ */
+#define HV_X64_CLUSTER_IPI_RECOMMENDED (1 << 10)
+
/* Recommend using the newer ExProcessorMasks interface */
#define HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED (1 << 11)

@@ -329,10 +334,14 @@ struct hv_tsc_emulation_status {
#define HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_MASK \
(~((1ull << HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT) - 1))

+#define HV_IPI_LOW_VECTOR 0x10
+#define HV_IPI_HIGH_VECTOR 0xff
+
/* Declare the various hypercall operations. */
#define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE 0x0002
#define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST 0x0003
#define HVCALL_NOTIFY_LONG_SPIN_WAIT 0x0008
+#define HVCALL_SEND_IPI 0x000b
#define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX 0x0013
#define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX 0x0014
#define HVCALL_POST_MESSAGE 0x005c
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index bcced50037c1..f6045f3611de 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -122,6 +122,7 @@ static inline void hv_disable_stimer0_percpu_irq(int irq) {}
#if IS_ENABLED(CONFIG_HYPERV)
extern struct clocksource *hyperv_cs;
extern void *hv_hypercall_pg;
+extern void __percpu **hyperv_pcpu_input_arg;

static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
{
--
2.15.1
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