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    Subject[PATCH V2 1/5] X86/Hyper-V: Add flush HvFlushGuestPhysicalAddressSpace hypercall support
    Date
    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>
    ---
    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 := 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
    index 000000000000..74dd38b5221d
    --- /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 published
    + * 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;
    + unsigned long flags;
    + int ret = -EFAULT;
    +
    + 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 b8c89265baf0..08e24f552030 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

    /* 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 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);

    #ifdef CONFIG_X86_64
    void hv_apic_init(void);
    @@ -321,6 +322,7 @@ 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
    --
    2.14.3
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