X86/Hyper-V: Add flush HvFlushGuestPhysicalAddressSpace hypercall support

Hyper-V supports a pv hypercall HvFlushGuestPhysicalAddressSpace to
flush nested VM address space mapping in l1 hypervisor and it's to
reduce overhead of flushing ept tlb among vcpus. This patch is to
implement it.

Signed-off-by: Lan Tianyu <Tianyu.Lan@microsoft.com>
Acked-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/hyperv/Makefile b/arch/x86/hyperv/Makefile
index b173d40..b21ee65 100644 (file)
--- a/arch/x86/hyperv/Makefile
+++ b/arch/x86/hyperv/Makefile
@@ -1,2 +1,2 @@
-obj-y                  := hv_init.o mmu.o
+obj-y                  := hv_init.o mmu.o nested.o
 obj-$(CONFIG_X86_64)   += hv_apic.o

diff --git a/arch/x86/hyperv/nested.c b/arch/x86/hyperv/nested.c
new file mode 100644 (file)
index 0000000..08f9142
--- /dev/null
+++ b/arch/x86/hyperv/nested.c
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Hyper-V nested virtualization code.
+ *
+ * Copyright (C) 2018, Microsoft, Inc.
+ *
+ * Author : Lan Tianyu <Tianyu.Lan@microsoft.com>
+ */
+
+
+#include <linux/types.h>
+#include <asm/hyperv-tlfs.h>
+#include <asm/mshyperv.h>
+#include <asm/tlbflush.h>
+
+int hyperv_flush_guest_mapping(u64 as)
+{
+       struct hv_guest_mapping_flush **flush_pcpu;
+       struct hv_guest_mapping_flush *flush;
+       u64 status;
+       unsigned long flags;
+       int ret = -ENOTSUPP;
+
+       if (!hv_hypercall_pg)
+               goto fault;
+
+       local_irq_save(flags);
+
+       flush_pcpu = (struct hv_guest_mapping_flush **)
+               this_cpu_ptr(hyperv_pcpu_input_arg);
+
+       flush = *flush_pcpu;
+
+       if (unlikely(!flush)) {
+               local_irq_restore(flags);
+               goto fault;
+       }
+
+       flush->address_space = as;
+       flush->flags = 0;
+
+       status = hv_do_hypercall(HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_SPACE,
+                                flush, NULL);
+       local_irq_restore(flags);
+
+       if (!(status & HV_HYPERCALL_RESULT_MASK))
+               ret = 0;
+
+fault:
+       return ret;
+}
+EXPORT_SYMBOL_GPL(hyperv_flush_guest_mapping);

diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index b8c8926..08e24f5 100644 (file)
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -309,6 +309,7 @@ struct ms_hyperv_tsc_page {
 #define HV_X64_MSR_REENLIGHTENMENT_CONTROL     0x40000106
 
 /* Nested features (CPUID 0x4000000A) EAX */
+#define HV_X64_NESTED_GUEST_MAPPING_FLUSH      BIT(18)
 #define HV_X64_NESTED_MSR_BITMAP               BIT(19)
 
 struct hv_reenlightenment_control {
@@ -350,6 +351,7 @@ struct hv_tsc_emulation_status {
 #define HVCALL_SEND_IPI_EX                     0x0015
 #define HVCALL_POST_MESSAGE                    0x005c
 #define HVCALL_SIGNAL_EVENT                    0x005d
+#define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_SPACE 0x00af
 
 #define HV_X64_MSR_VP_ASSIST_PAGE_ENABLE       0x00000001
 #define HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT        12
@@ -741,6 +743,12 @@ struct ipi_arg_ex {
        struct hv_vpset vp_set;
 };
 
+/* HvFlushGuestPhysicalAddressSpace hypercalls */
+struct hv_guest_mapping_flush {
+       u64 address_space;
+       u64 flags;
+};
+
 /* HvFlushVirtualAddressSpace, HvFlushVirtualAddressList hypercalls */
 struct hv_tlb_flush {
        u64 address_space;

diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 5a7375e..2519f5d 100644 (file)
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -305,6 +305,7 @@ void hyperv_reenlightenment_intr(struct pt_regs *regs);
 void set_hv_tscchange_cb(void (*cb)(void));
 void clear_hv_tscchange_cb(void);
 void hyperv_stop_tsc_emulation(void);
+int hyperv_flush_guest_mapping(u64 as);
 
 #ifdef CONFIG_X86_64
 void hv_apic_init(void);
@@ -324,6 +325,7 @@ static inline struct hv_vp_assist_page *hv_get_vp_assist_page(unsigned int cpu)
 {
        return NULL;
 }
+static inline int hyperv_flush_guest_mapping(u64 as) { return -1; }
 #endif /* CONFIG_HYPERV */
 
 #ifdef CONFIG_HYPERV_TSCPAGE