RE: [PATCH 1/5] X86: Hyper-V: Enlighten APIC access

["Michael Kelley (EOSG)" <Michael.H.Kelley@microsoft.com>]

> -----Original Message-----
> From: kys@linuxonhyperv.com <kys@linuxonhyperv.com>
> Sent: Wednesday, April 25, 2018 11:13 AM
> To: x86@kernel.org; gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org;
> devel@linuxdriverproject.org; olaf@aepfle.de; apw@canonical.com; jasowang@redhat.com;
> tglx@linutronix.de; hpa@zytor.com; Stephen Hemminger <sthemmin@microsoft.com>;
> Michael Kelley (EOSG) <Michael.H.Kelley@microsoft.com>; vkuznets@redhat.com
> Cc: KY Srinivasan <kys@microsoft.com>
> Subject: [PATCH 1/5] X86: Hyper-V: Enlighten APIC access
> 
> From: "K. Y. Srinivasan" <kys@microsoft.com>
> 
> Hyper-V supports MSR based APIC access; implement
> the enlightenment.
> 
> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
> ---
>  arch/x86/hyperv/Makefile        |  2 +-
>  arch/x86/hyperv/hv_apic.c       | 98 +++++++++++++++++++++++++++++++++++++++++
>  arch/x86/hyperv/hv_init.c       |  5 ++-
>  arch/x86/include/asm/mshyperv.h |  6 ++-
>  4 files changed, 107 insertions(+), 4 deletions(-)
>  create mode 100644 arch/x86/hyperv/hv_apic.c
> 
> diff --git a/arch/x86/hyperv/Makefile b/arch/x86/hyperv/Makefile
> index 367a8203cfcf..00ce4df01a09 100644
> --- a/arch/x86/hyperv/Makefile
> +++ b/arch/x86/hyperv/Makefile
> @@ -1 +1 @@
> -obj-y		:= hv_init.o mmu.o
> +obj-y		:= hv_init.o mmu.o hv_apic.o
> diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c
> new file mode 100644
> index 000000000000..e0a5b36208fc
> --- /dev/null
> +++ b/arch/x86/hyperv/hv_apic.c
> @@ -0,0 +1,98 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/*
> + * Hyper-V specific APIC code.
> + *
> + * Copyright (C) 2018, Microsoft, Inc.
> + *
> + * Author : K. Y. Srinivasan <kys@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/hypervisor.h>
> +#include <asm/mshyperv.h>
> +#include <linux/version.h>
> +#include <linux/vmalloc.h>
> +#include <linux/mm.h>
> +#include <linux/clockchips.h>
> +#include <linux/hyperv.h>
> +#include <linux/slab.h>
> +#include <linux/cpuhotplug.h>
> +
> +static u64 hv_apic_icr_read(void)
> +{
> +	u64 reg_val;
> +
> +	rdmsrl(HV_X64_MSR_ICR, reg_val);
> +	return reg_val;
> +}
> +
> +static void hv_apic_icr_write(u32 low, u32 id)
> +{
> +	u64 reg_val;
> +
> +	reg_val = SET_APIC_DEST_FIELD(id);
> +	reg_val = reg_val << 32;
> +	reg_val |= low;
> +
> +	wrmsrl(HV_X64_MSR_ICR, reg_val);
> +}
> +
> +static u32 hv_apic_read(u32 reg)
> +{
> +	u32 reg_val, hi;
> +
> +	switch (reg) {
> +	case APIC_EOI:
> +		rdmsr(HV_X64_MSR_EOI, reg_val, hi);
> +		return reg_val;
> +	case APIC_TASKPRI:
> +		rdmsr(HV_X64_MSR_TPR, reg_val, hi);
> +		return reg_val;
> +
> +	default:
> +		return native_apic_mem_read(reg);
> +	}
> +}
> +
> +static void hv_apic_write(u32 reg, u32 val)
> +{
> +	switch (reg) {
> +	case APIC_EOI:
> +		wrmsr(HV_X64_MSR_EOI, val, 0);
> +		break;
> +	case APIC_TASKPRI:
> +		wrmsr(HV_X64_MSR_TPR, val, 0);
> +		break;
> +	default:
> +		native_apic_mem_write(reg, val);
> +	}
> +}
> +
> +static void hv_apic_eoi_write(u32 reg, u32 val)
> +{
> +	wrmsr(HV_X64_MSR_EOI, val, 0);
> +}
> +
> +void __init hv_apic_init(void)
> +{
> +	if (ms_hyperv.hints & HV_X64_APIC_ACCESS_RECOMMENDED) {
> +		pr_info("Hyper-V: Using MSR ased APIC access\n");

Typo here.  "ased" should be "based".

> +		apic_set_eoi_write(hv_apic_eoi_write);
> +		apic->read      = hv_apic_read;
> +		apic->write     = hv_apic_write;
> +		apic->icr_write = hv_apic_icr_write;
> +		apic->icr_read  = hv_apic_icr_read;
> +	}
> +}
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index cfecc2272f2d..71e50fc2b7ef 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -242,8 +242,9 @@ static int hv_cpu_die(unsigned int cpu)
>   *
>   * 1. Setup the hypercall page.
>   * 2. Register Hyper-V specific clocksource.
> + * 3. Setup Hyper-V specific APIC entry points.
>   */
> -void hyperv_init(void)
> +void __init hyperv_init(void)
>  {
>  	u64 guest_id, required_msrs;
>  	union hv_x64_msr_hypercall_contents hypercall_msr;
> @@ -298,6 +299,8 @@ void hyperv_init(void)
> 
>  	hyper_alloc_mmu();
> 
> +	hv_apic_init();
> +
>  	/*
>  	 * Register Hyper-V specific clocksource.
>  	 */
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index b90e79610cf7..bcced50037c1 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -258,7 +258,7 @@ static inline int hv_cpu_number_to_vp_number(int cpu_number)
>  	return hv_vp_index[cpu_number];
>  }
> 
> -void hyperv_init(void);
> +void __init hyperv_init(void);
>  void hyperv_setup_mmu_ops(void);
>  void hyper_alloc_mmu(void);
>  void hyperv_report_panic(struct pt_regs *regs, long err);
> @@ -269,14 +269,16 @@ 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);
> +void hv_apic_init(void);
>  #else /* CONFIG_HYPERV */
> -static inline void hyperv_init(void) {}
> +static __init  inline void hyperv_init(void) {}
>  static inline bool hv_is_hyperv_initialized(void) { return false; }
>  static inline void hyperv_cleanup(void) {}
>  static inline void hyperv_setup_mmu_ops(void) {}
>  static inline void set_hv_tscchange_cb(void (*cb)(void)) {}
>  static inline void clear_hv_tscchange_cb(void) {}
>  static inline void hyperv_stop_tsc_emulation(void) {};
> +static inline void hv_apic_init(void) {}
>  static inline struct hv_vp_assist_page *hv_get_vp_assist_page(unsigned int cpu)
>  {
>  	return NULL;
> --
> 2.15.1

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