[PATCH 3/5] X86: Hyper-V: Enhanced IPI enlightenment

[kys@linuxonhyperv.com]

From: "K. Y. Srinivasan" <kys@microsoft.com>

Support enhanced IPI enlightenments (to target more than 64 CPUs).

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 arch/x86/hyperv/hv_apic.c          | 49 ++++++++++++++++++++++++++++++++++++--
 arch/x86/include/asm/hyperv-tlfs.h |  1 +
 arch/x86/include/asm/mshyperv.h    | 39 ++++++++++++++++++++++++++++++
 3 files changed, 87 insertions(+), 2 deletions(-)

diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c
index 7f3322ecfb01..fbb408b91e25 100644
--- a/arch/x86/hyperv/hv_apic.c
+++ b/arch/x86/hyperv/hv_apic.c
@@ -36,6 +36,12 @@ struct ipi_arg_non_ex {
 	u64 cpu_mask;
 };
 
+struct ipi_arg_ex {
+	u32 vector;
+	u32  reserved;
+	struct hv_vpset vp_set;
+};
+
 static struct apic orig_apic;
 
 static u64 hv_apic_icr_read(void)
@@ -97,6 +103,40 @@ static void hv_apic_eoi_write(u32 reg, u32 val)
  * IPI implementation on Hyper-V.
  */
 
+static int __send_ipi_mask_ex(const struct cpumask *mask, int vector)
+{
+	int nr_bank = 0;
+	struct ipi_arg_ex **arg;
+	struct ipi_arg_ex *ipi_arg;
+	int ret = 1;
+	unsigned long flags;
+
+	local_irq_save(flags);
+	arg = (struct ipi_arg_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
+
+	ipi_arg = *arg;
+	if (unlikely(!ipi_arg))
+		goto ipi_mask_ex_done;
+
+	ipi_arg->vector = vector;
+	ipi_arg->reserved = 0;
+	ipi_arg->vp_set.valid_bank_mask = 0;
+
+	if (!cpumask_equal(mask, cpu_present_mask)) {
+		ipi_arg->vp_set.format = HV_GENERIC_SET_SPARCE_4K;
+		nr_bank = cpumask_to_vpset(&(ipi_arg->vp_set), mask);
+	}
+	if (!nr_bank)
+		ipi_arg->vp_set.format = HV_GENERIC_SET_ALL;
+
+	ret = hv_do_rep_hypercall(HVCALL_SEND_IPI_EX, 0, nr_bank,
+			      ipi_arg, NULL);
+
+ipi_mask_ex_done:
+	local_irq_restore(flags);
+	return ret;
+}
+
 static int __send_ipi_mask(const struct cpumask *mask, int vector)
 {
 	int cur_cpu, vcpu;
@@ -114,6 +154,9 @@ static int __send_ipi_mask(const struct cpumask *mask, int vector)
 	if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR))
 		return ret;
 
+	if ((ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED))
+		return __send_ipi_mask_ex(mask, vector);
+
 	local_irq_save(flags);
 	arg = (struct ipi_arg_non_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
 
@@ -196,8 +239,10 @@ 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");
+		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.
 		 */
diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index 646cf2ca2aaa..53ea30d768d9 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -344,6 +344,7 @@ struct hv_tsc_emulation_status {
 #define HVCALL_SEND_IPI				0x000b
 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX  0x0013
 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX   0x0014
+#define HVCALL_SEND_IPI_EX			0x0015
 #define HVCALL_POST_MESSAGE			0x005c
 #define HVCALL_SIGNAL_EVENT			0x005d
 
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index f6045f3611de..956e8603bed2 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -259,6 +259,45 @@ static inline int hv_cpu_number_to_vp_number(int cpu_number)
 	return hv_vp_index[cpu_number];
 }
 
+struct hv_vpset {
+	u64 format;
+	u64 valid_bank_mask;
+	u64 bank_contents[];
+};
+
+static inline int cpumask_to_vpset(struct hv_vpset *vpset,
+				    const struct cpumask *cpus)
+{
+	int cpu, vcpu, vcpu_bank, vcpu_offset, nr_bank = 1;
+
+	/* valid_bank_mask can represent up to 64 banks */
+	if (hv_max_vp_index / 64 >= 64)
+		return 0;
+
+	/*
+	 * Clear all banks up to the maximum possible bank as hv_flush_pcpu_ex
+	 * structs are not cleared between calls, we risk flushing unneeded
+	 * vCPUs otherwise.
+	 */
+	for (vcpu_bank = 0; vcpu_bank <= hv_max_vp_index / 64; vcpu_bank++)
+		vpset->bank_contents[vcpu_bank] = 0;
+
+	/*
+	 * Some banks may end up being empty but this is acceptable.
+	 */
+	for_each_cpu(cpu, cpus) {
+		vcpu = hv_cpu_number_to_vp_number(cpu);
+		vcpu_bank = vcpu / 64;
+		vcpu_offset = vcpu % 64;
+		__set_bit(vcpu_offset, (unsigned long *)
+			  &vpset->bank_contents[vcpu_bank]);
+		if (vcpu_bank >= nr_bank)
+			nr_bank = vcpu_bank + 1;
+	}
+	vpset->valid_bank_mask = GENMASK_ULL(nr_bank - 1, 0);
+	return nr_bank;
+}
+
 void __init hyperv_init(void);
 void hyperv_setup_mmu_ops(void);
 void hyper_alloc_mmu(void);
-- 
2.15.1