summaryrefslogtreecommitdiff
path: root/arch/x86/hyperv/mmu.c
diff options
context:
space:
mode:
authorVitaly Kuznetsov <vkuznets@redhat.com>2017-08-02 19:09:19 +0300
committerIngo Molnar <mingo@kernel.org>2017-08-10 21:16:44 +0300
commit2ffd9e33ce4af4e8cfa3e17bf493defe8474e2eb (patch)
tree47f4afe37d6bf0e6e0219ab1b08ca45fc692aa47 /arch/x86/hyperv/mmu.c
parent7415aea6072bab15969b6c3c5b2a193d88095326 (diff)
downloadlinux-2ffd9e33ce4af4e8cfa3e17bf493defe8474e2eb.tar.xz
x86/hyper-v: Use hypercall for remote TLB flush
Hyper-V host can suggest us to use hypercall for doing remote TLB flush, this is supposed to work faster than IPIs. Implementation details: to do HvFlushVirtualAddress{Space,List} hypercalls we need to put the input somewhere in memory and we don't really want to have memory allocation on each call so we pre-allocate per cpu memory areas on boot. pv_ops patching is happening very early so we need to separate hyperv_setup_mmu_ops() and hyper_alloc_mmu(). It is possible and easy to implement local TLB flushing too and there is even a hint for that. However, I don't see a room for optimization on the host side as both hypercall and native tlb flush will result in vmexit. The hint is also not set on modern Hyper-V versions. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Reviewed-by: Stephen Hemminger <sthemmin@microsoft.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Jork Loeser <Jork.Loeser@microsoft.com> Cc: K. Y. Srinivasan <kys@microsoft.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Simon Xiao <sixiao@microsoft.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: devel@linuxdriverproject.org Link: http://lkml.kernel.org/r/20170802160921.21791-8-vkuznets@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/hyperv/mmu.c')
-rw-r--r--arch/x86/hyperv/mmu.c138
1 files changed, 138 insertions, 0 deletions
diff --git a/arch/x86/hyperv/mmu.c b/arch/x86/hyperv/mmu.c
new file mode 100644
index 000000000000..9419a20b1d75
--- /dev/null
+++ b/arch/x86/hyperv/mmu.c
@@ -0,0 +1,138 @@
+#define pr_fmt(fmt) "Hyper-V: " fmt
+
+#include <linux/hyperv.h>
+#include <linux/log2.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#include <asm/fpu/api.h>
+#include <asm/mshyperv.h>
+#include <asm/msr.h>
+#include <asm/tlbflush.h>
+
+/* HvFlushVirtualAddressSpace, HvFlushVirtualAddressList hypercalls */
+struct hv_flush_pcpu {
+ u64 address_space;
+ u64 flags;
+ u64 processor_mask;
+ 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;
+
+/*
+ * Fills in gva_list starting from offset. Returns the number of items added.
+ */
+static inline int fill_gva_list(u64 gva_list[], int offset,
+ unsigned long start, unsigned long end)
+{
+ int gva_n = offset;
+ unsigned long cur = start, diff;
+
+ do {
+ diff = end > cur ? end - cur : 0;
+
+ gva_list[gva_n] = cur & PAGE_MASK;
+ /*
+ * Lower 12 bits encode the number of additional
+ * pages to flush (in addition to the 'cur' page).
+ */
+ if (diff >= HV_TLB_FLUSH_UNIT)
+ gva_list[gva_n] |= ~PAGE_MASK;
+ else if (diff)
+ gva_list[gva_n] |= (diff - 1) >> PAGE_SHIFT;
+
+ cur += HV_TLB_FLUSH_UNIT;
+ gva_n++;
+
+ } while (cur < end);
+
+ return gva_n - offset;
+}
+
+static void hyperv_flush_tlb_others(const struct cpumask *cpus,
+ const struct flush_tlb_info *info)
+{
+ int cpu, vcpu, gva_n, max_gvas;
+ struct hv_flush_pcpu *flush;
+ u64 status = U64_MAX;
+ unsigned long flags;
+
+ if (!pcpu_flush || !hv_hypercall_pg)
+ goto do_native;
+
+ if (cpumask_empty(cpus))
+ return;
+
+ local_irq_save(flags);
+
+ flush = this_cpu_ptr(pcpu_flush);
+
+ 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->processor_mask = 0;
+ if (cpumask_equal(cpus, cpu_present_mask)) {
+ flush->flags |= HV_FLUSH_ALL_PROCESSORS;
+ } else {
+ for_each_cpu(cpu, cpus) {
+ vcpu = hv_cpu_number_to_vp_number(cpu);
+ if (vcpu >= 64)
+ goto do_native;
+
+ __set_bit(vcpu, (unsigned long *)
+ &flush->processor_mask);
+ }
+ }
+
+ /*
+ * 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)) / sizeof(flush->gva_list[0]);
+
+ if (info->end == TLB_FLUSH_ALL) {
+ flush->flags |= HV_FLUSH_NON_GLOBAL_MAPPINGS_ONLY;
+ status = hv_do_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE,
+ flush, NULL);
+ } else if (info->end &&
+ ((info->end - info->start)/HV_TLB_FLUSH_UNIT) > max_gvas) {
+ status = hv_do_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE,
+ flush, NULL);
+ } else {
+ gva_n = fill_gva_list(flush->gva_list, 0,
+ info->start, info->end);
+ status = hv_do_rep_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST,
+ gva_n, 0, 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) {
+ 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);
+ }
+}
+
+void hyper_alloc_mmu(void)
+{
+ if (ms_hyperv.hints & HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED)
+ pcpu_flush = __alloc_percpu(PAGE_SIZE, PAGE_SIZE);
+}