[tip:x86/platform] x86/hyper-v: Support extended CPU ranges for TLB flush hypercalls

From: tip-bot for Vitaly Kuznetsov
Date: Thu Aug 31 2017 - 16:06:07 EST

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Commit-ID: 628f54cc6451d2706ba8a56763dbf93be02aaa80
Gitweb: http://git.kernel.org/tip/628f54cc6451d2706ba8a56763dbf93be02aaa80
Author: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
AuthorDate: Wed, 2 Aug 2017 18:09:20 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 31 Aug 2017 14:20:36 +0200

x86/hyper-v: Support extended CPU ranges for TLB flush hypercalls

Hyper-V hosts may support more than 64 vCPUs, we need to use
HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX/LIST_EX hypercalls in this
case.

Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Reviewed-by: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
Cc: Jork Loeser <Jork.Loeser@xxxxxxxxxxxxx>
Cc: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Simon Xiao <sixiao@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: devel@xxxxxxxxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20170802160921.21791-9-vkuznets@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/hyperv/mmu.c | 133 ++++++++++++++++++++++++++++++++++++-
arch/x86/include/uapi/asm/hyperv.h | 10 +++
2 files changed, 140 insertions(+), 3 deletions(-)

diff --git a/arch/x86/hyperv/mmu.c b/arch/x86/hyperv/mmu.c
index 9419a20..51b44be 100644
--- a/arch/x86/hyperv/mmu.c
+++ b/arch/x86/hyperv/mmu.c
@@ -18,11 +18,25 @@ struct hv_flush_pcpu {
u64 gva_list[];
};

+/* HvFlushVirtualAddressSpaceEx, HvFlushVirtualAddressListEx hypercalls */
+struct hv_flush_pcpu_ex {
+ u64 address_space;
+ u64 flags;
+ struct {
+ u64 format;
+ u64 valid_bank_mask;
+ u64 bank_contents[];
+ } hv_vp_set;
+ u64 gva_list[];
+};
+
/* Each gva in gva_list encodes up to 4096 pages to flush */
#define HV_TLB_FLUSH_UNIT (4096 * PAGE_SIZE)

static struct hv_flush_pcpu __percpu *pcpu_flush;

+static struct hv_flush_pcpu_ex __percpu *pcpu_flush_ex;
+
/*
* Fills in gva_list starting from offset. Returns the number of items added.
*/
@@ -53,6 +67,34 @@ static inline int fill_gva_list(u64 gva_list[], int offset,
return gva_n - offset;
}

+/* Return the number of banks in the resulting vp_set */
+static inline int cpumask_to_vp_set(struct hv_flush_pcpu_ex *flush,
+ const struct cpumask *cpus)
+{
+ int cpu, vcpu, vcpu_bank, vcpu_offset, nr_bank = 1;
+
+ /*
+ * 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;
+
+ /* valid_bank_mask can represent up to 64 banks */
+ if (vcpu_bank >= 64)
+ return 0;
+
+ __set_bit(vcpu_offset, (unsigned long *)
+ &flush->hv_vp_set.bank_contents[vcpu_bank]);
+ if (vcpu_bank >= nr_bank)
+ nr_bank = vcpu_bank + 1;
+ }
+ flush->hv_vp_set.valid_bank_mask = GENMASK_ULL(nr_bank - 1, 0);
+
+ return nr_bank;
+}
+
static void hyperv_flush_tlb_others(const struct cpumask *cpus,
const struct flush_tlb_info *info)
{
@@ -122,17 +164,102 @@ do_native:
native_flush_tlb_others(cpus, info);
}

+static void hyperv_flush_tlb_others_ex(const struct cpumask *cpus,
+ const struct flush_tlb_info *info)
+{
+ int nr_bank = 0, max_gvas, gva_n;
+ struct hv_flush_pcpu_ex *flush;
+ u64 status = U64_MAX;
+ unsigned long flags;
+
+ if (!pcpu_flush_ex || !hv_hypercall_pg)
+ goto do_native;
+
+ if (cpumask_empty(cpus))
+ return;
+
+ local_irq_save(flags);
+
+ flush = this_cpu_ptr(pcpu_flush_ex);
+
+ if (info->mm) {
+ flush->address_space = virt_to_phys(info->mm->pgd);
+ flush->flags = 0;
+ } else {
+ flush->address_space = 0;
+ flush->flags = HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES;
+ }
+
+ flush->hv_vp_set.valid_bank_mask = 0;
+
+ if (!cpumask_equal(cpus, cpu_present_mask)) {
+ flush->hv_vp_set.format = HV_GENERIC_SET_SPARCE_4K;
+ nr_bank = cpumask_to_vp_set(flush, cpus);
+ }
+
+ if (!nr_bank) {
+ flush->hv_vp_set.format = HV_GENERIC_SET_ALL;
+ flush->flags |= HV_FLUSH_ALL_PROCESSORS;
+ }
+
+ /*
+ * We can flush not more than max_gvas with one hypercall. Flush the
+ * whole address space if we were asked to do more.
+ */
+ max_gvas =
+ (PAGE_SIZE - sizeof(*flush) - nr_bank *
+ sizeof(flush->hv_vp_set.bank_contents[0])) /
+ sizeof(flush->gva_list[0]);
+
+ if (info->end == TLB_FLUSH_ALL) {
+ flush->flags |= HV_FLUSH_NON_GLOBAL_MAPPINGS_ONLY;
+ status = hv_do_rep_hypercall(
+ HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX,
+ 0, nr_bank + 2, flush, NULL);
+ } else if (info->end &&
+ ((info->end - info->start)/HV_TLB_FLUSH_UNIT) > max_gvas) {
+ status = hv_do_rep_hypercall(
+ HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX,
+ 0, nr_bank + 2, flush, NULL);
+ } else {
+ gva_n = fill_gva_list(flush->gva_list, nr_bank,
+ info->start, info->end);
+ status = hv_do_rep_hypercall(
+ HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX,
+ gva_n, nr_bank + 2, flush, NULL);
+ }
+
+ local_irq_restore(flags);
+
+ if (!(status & HV_HYPERCALL_RESULT_MASK))
+ return;
+do_native:
+ native_flush_tlb_others(cpus, info);
+}
+
void hyperv_setup_mmu_ops(void)
{
- if (ms_hyperv.hints & HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED) {
+ if (!(ms_hyperv.hints & HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED))
+ return;
+
+ setup_clear_cpu_cap(X86_FEATURE_PCID);
+
+ if (!(ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED)) {
pr_info("Using hypercall for remote TLB flush\n");
pv_mmu_ops.flush_tlb_others = hyperv_flush_tlb_others;
- setup_clear_cpu_cap(X86_FEATURE_PCID);
+ } else {
+ pr_info("Using ext hypercall for remote TLB flush\n");
+ pv_mmu_ops.flush_tlb_others = hyperv_flush_tlb_others_ex;
}
}

void hyper_alloc_mmu(void)
{
- if (ms_hyperv.hints & HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED)
+ if (!(ms_hyperv.hints & HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED))
+ return;
+
+ if (!(ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED))
pcpu_flush = __alloc_percpu(PAGE_SIZE, PAGE_SIZE);
+ else
+ pcpu_flush_ex = __alloc_percpu(PAGE_SIZE, PAGE_SIZE);
}
diff --git a/arch/x86/include/uapi/asm/hyperv.h b/arch/x86/include/uapi/asm/hyperv.h
index a6fdd3b..7032f4d 100644
--- a/arch/x86/include/uapi/asm/hyperv.h
+++ b/arch/x86/include/uapi/asm/hyperv.h
@@ -149,6 +149,9 @@
*/
#define HV_X64_DEPRECATING_AEOI_RECOMMENDED (1 << 9)

+/* Recommend using the newer ExProcessorMasks interface */
+#define HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED (1 << 11)
+
/*
* HV_VP_SET available
*/
@@ -245,6 +248,8 @@
#define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE 0x0002
#define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST 0x0003
#define HVCALL_NOTIFY_LONG_SPIN_WAIT 0x0008
+#define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX 0x0013
+#define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX 0x0014
#define HVCALL_POST_MESSAGE 0x005c
#define HVCALL_SIGNAL_EVENT 0x005d

@@ -266,6 +271,11 @@
#define HV_FLUSH_NON_GLOBAL_MAPPINGS_ONLY BIT(2)
#define HV_FLUSH_USE_EXTENDED_RANGE_FORMAT BIT(3)

+enum HV_GENERIC_SET_FORMAT {
+ HV_GENERIC_SET_SPARCE_4K,
+ HV_GENERIC_SET_ALL,
+};
+
/* hypercall status code */
#define HV_STATUS_SUCCESS 0
#define HV_STATUS_INVALID_HYPERCALL_CODE 2

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