X86/Hyper-V: Add flush HvFlushGuestPhysicalAddressSpace hypercall support

Tianyu Lan · bonzini · commit eb914cfe72f4 · 2018-08-06T17:59:04.000+02:00
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 &lt;Tianyu.Lan@microsoft.com&gt;
Acked-by: K. Y. Srinivasan &lt;kys@microsoft.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
diff --git 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
@@ -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
@@ -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
@@ -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

Original file line number	Diff line number	Diff line change
`@@ -1,2 +1,2 @@`
`1`		`-obj-y := hv_init.o mmu.o`
	`1`	`+obj-y := hv_init.o mmu.o nested.o`
`2`	`2`	`obj-$(CONFIG_X86_64) += hv_apic.o`
Original file line number	Diff line number	Diff line change
`@@ -305,6 +305,7 @@ void hyperv_reenlightenment_intr(struct pt_regs *regs);`
`305`	`305`	`void set_hv_tscchange_cb(void (*cb)(void));`
`306`	`306`	`void clear_hv_tscchange_cb(void);`
`307`	`307`	`void hyperv_stop_tsc_emulation(void);`
	`308`	`+int hyperv_flush_guest_mapping(u64 as);`
`308`	`309`
`309`	`310`	`#ifdef CONFIG_X86_64`
`310`	`311`	`void hv_apic_init(void);`
`@@ -324,6 +325,7 @@ static inline struct hv_vp_assist_page *hv_get_vp_assist_page(unsigned int cpu)`
`324`	`325`	`{`
`325`	`326`	`return NULL;`
`326`	`327`	`}`
	`328`	`+static inline int hyperv_flush_guest_mapping(u64 as) { return -1; }`
`327`	`329`	`#endif /* CONFIG_HYPERV */`
`328`	`330`
`329`	`331`	`#ifdef CONFIG_HYPERV_TSCPAGE`