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From:   Tianyu Lan <Tianyu.Lan@microsoft.com>
CC:     Tianyu Lan <Tianyu.Lan@microsoft.com>,
        KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
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        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "vkuznets@redhat.com" <vkuznets@redhat.com>
Subject: [RFC Patch 1/3] X86/Hyper-V: Add flush
 HvFlushGuestPhysicalAddressSpace hypercall support
Thread-Topic: [RFC Patch 1/3] X86/Hyper-V: Add flush
 HvFlushGuestPhysicalAddressSpace hypercall support
Thread-Index: AQHT++OW1TQj7xYFtUGQsOkMiGidAQ==
Date:   Mon, 4 Jun 2018 09:08:23 +0000
Message-ID: <20180604090749.489-2-Tianyu.Lan@microsoft.com>
References: <20180604090749.489-1-Tianyu.Lan@microsoft.com>
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Hyper-V provides a pv hypercall HvFlushGuestPhysicalAddressSpace to flush
nested VM address space mapping in l1 hypervisor and it's to reduce overhea=
d
of flushing ept tlb among vcpus. This patch is to implement it.

Signed-off-by: Lan Tianyu <Tianyu.Lan@microsoft.com>
---
 arch/x86/hyperv/Makefile           |  2 +-
 arch/x86/hyperv/nested.c           | 64 ++++++++++++++++++++++++++++++++++=
++++
 arch/x86/include/asm/hyperv-tlfs.h |  8 +++++
 arch/x86/include/asm/mshyperv.h    |  2 ++
 4 files changed, 75 insertions(+), 1 deletion(-)
 create mode 100644 arch/x86/hyperv/nested.c

diff --git a/arch/x86/hyperv/Makefile b/arch/x86/hyperv/Makefile
index b173d404e3df..b21ee65c4101 100644
--- a/arch/x86/hyperv/Makefile
+++ b/arch/x86/hyperv/Makefile
@@ -1,2 +1,2 @@
-obj-y			:=3D hv_init.o mmu.o
+obj-y			:=3D hv_init.o mmu.o nested.o
 obj-$(CONFIG_X86_64)	+=3D hv_apic.o
diff --git a/arch/x86/hyperv/nested.c b/arch/x86/hyperv/nested.c
new file mode 100644
index 000000000000..17f7c288eccc
--- /dev/null
+++ b/arch/x86/hyperv/nested.c
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Hyper-V nested virtualization code.
+ *
+ * Copyright (C) 2018, Microsoft, Inc.
+ *
+ * Author : Lan Tianyu <Tianyu.Lan@microsoft.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as publishe=
d
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ *
+ */
+
+
+#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 =3D U64_MAX;
+	unsigned long flags;
+	int ret =3D -EFAULT;
+
+	if (!hv_hypercall_pg)
+		goto fault;
+
+	local_irq_save(flags);
+
+	flush_pcpu =3D (struct hv_guest_mapping_flush **)
+		this_cpu_ptr(hyperv_pcpu_input_arg);
+
+	flush =3D *flush_pcpu;
+
+	if (unlikely(!flush)) {
+		local_irq_restore(flags);
+		goto fault;
+	}
+
+	flush->address_space =3D as;
+	flush->flags =3D 0;
+
+	status =3D hv_do_hypercall(HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_SPACE,
+				 flush, NULL);
+	local_irq_restore(flags);
+
+	if (!(status & HV_HYPERCALL_RESULT_MASK))
+		ret =3D 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/hype=
rv-tlfs.h
index b8c89265baf0..53bbeb08faea 100644
--- 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
=20
 /* Nested features (CPUID 0x4000000A) EAX */
+#define HV_X64_NESTED_GUSET_MAPPING_FLUSH	BIT(18)
 #define HV_X64_NESTED_MSR_BITMAP		BIT(19)
=20
 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
=20
 #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;
 };
=20
+/* 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/mshyper=
v.h
index 3cd14311edfa..a6a615b49876 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -302,6 +302,7 @@ 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);
=20
 #ifdef CONFIG_X86_64
 void hv_apic_init(void);
@@ -321,6 +322,7 @@ static inline struct hv_vp_assist_page *hv_get_vp_assis=
t_page(unsigned int cpu)
 {
 	return NULL;
 }
+static inline int hyperv_flush_guest_mapping(u64 as) { return -1; }
 #endif /* CONFIG_HYPERV */
=20
 #ifdef CONFIG_HYPERV_TSCPAGE
--=20
2.14.3