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SubjectRe: [PATCH v3 4/4] x86/hyperv: Mark "hv_nopvspin" parameter obsolete and map it to "nopvspin"
On Mon, Sep 30, 2019 at 08:44:39PM +0800, Zhenzhong Duan wrote:
> Includes asm/hypervisor.h in order to reference x86_hyper_type.
>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: "K. Y. Srinivasan" <kys@microsoft.com>
> Cc: Haiyang Zhang <haiyangz@microsoft.com>
> Cc: Stephen Hemminger <sthemmin@microsoft.com>
> Cc: Sasha Levin <sashal@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> ---
> Documentation/admin-guide/kernel-parameters.txt | 6 +++++-
> arch/x86/hyperv/hv_spinlock.c | 9 +++++----
> 2 files changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 1f0a62f..43f922c 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -1436,6 +1436,10 @@
> hv_nopvspin [X86,HYPER_V] Disables the paravirt spinlock optimizations
> which allow the hypervisor to 'idle' the
> guest on lock contention.
> + This parameter is obsoleted by "nopvspin"
> + parameter, which has equivalent effect for
> + HYPER_V platform.
> +
>
> keep_bootcon [KNL]
> Do not unregister boot console at start. This is only
> @@ -5331,7 +5335,7 @@
> as generic guest with no PV drivers. Currently support
> XEN HVM, KVM, HYPER_V and VMWARE guest.
>
> - nopvspin [X86,XEN,KVM] Disables the qspinlock slow path
> + nopvspin [X86,XEN,KVM,HYPER_V] Disables the qspinlock slow path
> using PV optimizations which allow the hypervisor to
> 'idle' the guest on lock contention.
>
> diff --git a/arch/x86/hyperv/hv_spinlock.c b/arch/x86/hyperv/hv_spinlock.c
> index 07f21a0..e00e319 100644
> --- a/arch/x86/hyperv/hv_spinlock.c
> +++ b/arch/x86/hyperv/hv_spinlock.c
> @@ -12,12 +12,11 @@
>
> #include <linux/spinlock.h>
>
> +#include <asm/hypervisor.h>
> #include <asm/mshyperv.h>
> #include <asm/paravirt.h>
> #include <asm/apic.h>
>
> -static bool __initdata hv_pvspin = true;
> -
> static void hv_qlock_kick(int cpu)
> {
> apic->send_IPI(cpu, X86_PLATFORM_IPI_VECTOR);
> @@ -64,7 +63,7 @@ __visible bool hv_vcpu_is_preempted(int vcpu)
>
> void __init hv_init_spinlocks(void)
> {
> - if (!hv_pvspin || !apic ||
> + if (!pvspin || !apic ||
> !(ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) ||
> !(ms_hyperv.features & HV_X64_MSR_GUEST_IDLE_AVAILABLE)) {
> pr_info("PV spinlocks disabled\n");
> @@ -82,7 +81,9 @@ void __init hv_init_spinlocks(void)
>
> static __init int hv_parse_nopvspin(char *arg)
> {
> - hv_pvspin = false;
> + pr_notice("\"hv_nopvspin\" is deprecated, please use \"nopvspin\" instead\n");
> + if (x86_hyper_type == X86_HYPER_MS_HYPERV)
> + pvspin = false;

Personal preference would be to keep the hv_pvspin variable and add the
extra check in hv_init_spinlocks().

> return 0;
> }
> early_param("hv_nopvspin", hv_parse_nopvspin);
> --
> 1.8.3.1
>

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