linux-kernel - RE: [PATCH 1/1] X86: Fix the circular dependency in IPI enlightenment.

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Message-ID: <BL0PR2101MB1107AC5048311B0AC1C6A852A0420@BL0PR2101MB1107.namprd21.prod.outlook.com>
Date:   Tue, 3 Jul 2018 22:44:36 +0000
From:   KY Srinivasan <kys@...rosoft.com>
To:     KY Srinivasan <kys@...rosoft.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
        "olaf@...fle.de" <olaf@...fle.de>,
        "apw@...onical.com" <apw@...onical.com>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "hpa@...or.com" <hpa@...or.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        "Michael Kelley (EOSG)" <Michael.H.Kelley@...rosoft.com>,
        "vkuznets@...hat.com" <vkuznets@...hat.com>
Subject: RE: [PATCH 1/1] X86: Fix the circular dependency in IPI
 enlightenment.



> -----Original Message-----
> From: kys@...uxonhyperv.com <kys@...uxonhyperv.com>
> Sent: Tuesday, July 3, 2018 3:37 PM
> To: x86@...nel.org; gregkh@...uxfoundation.org; linux-
> kernel@...r.kernel.org; devel@...uxdriverproject.org; olaf@...fle.de;
> apw@...onical.com; jasowang@...hat.com; tglx@...utronix.de;
> hpa@...or.com; Stephen Hemminger <sthemmin@...rosoft.com>; Michael
> Kelley (EOSG) <Michael.H.Kelley@...rosoft.com>; vkuznets@...hat.com
> Cc: KY Srinivasan <kys@...rosoft.com>
> Subject: [PATCH 1/1] X86: Fix the circular dependency in IPI enlightenment.
> 
> From: "K. Y. Srinivasan" <kys@...rosoft.com>
> 
> The IPI hypercalls depend on being able to map the Linux notion of CPU ID
> to the hypervisor's notion of the CPU ID. The array hv_vp_index[] provides
> this mapping. Code for populating this array depends on the IPI functionality.
> Break this circular dependency.
> 
> Fixes: 68bb7bfb7985 ("X86/Hyper-V: Enable IPI enlightenments")

Please drop this patch; I have sent the wrong patch.

Regards,

K. Y
> 
> Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
> Tested-by: Michael Kelley <mikelley@...rosoft.com>
> ---
>  arch/x86/hyperv/hv_apic.c       | 5 +++++
>  arch/x86/hyperv/hv_init.c       | 3 +++
>  arch/x86/include/asm/mshyperv.h | 2 ++
>  3 files changed, 10 insertions(+)
> 
> diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c
> index f68855499391..63d7c196739f 100644
> --- a/arch/x86/hyperv/hv_apic.c
> +++ b/arch/x86/hyperv/hv_apic.c
> @@ -114,6 +114,8 @@ static bool __send_ipi_mask_ex(const struct cpumask
> *mask, int vector)
>  		ipi_arg->vp_set.format = HV_GENERIC_SET_SPARSE_4K;
>  		nr_bank = cpumask_to_vpset(&(ipi_arg->vp_set), mask);
>  	}
> +	if (nr_bank == -1)
> +		goto ipi_mask_ex_done;
>  	if (!nr_bank)
>  		ipi_arg->vp_set.format = HV_GENERIC_SET_ALL;
> 
> @@ -158,6 +160,9 @@ static bool __send_ipi_mask(const struct cpumask
> *mask, int vector)
> 
>  	for_each_cpu(cur_cpu, mask) {
>  		vcpu = hv_cpu_number_to_vp_number(cur_cpu);
> +		if (vcpu == -1)
> +			goto ipi_mask_done;
> +
>  		/*
>  		 * This particular version of the IPI hypercall can
>  		 * only target upto 64 CPUs.
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index 595e44e8abaa..762ce164d733 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -293,6 +293,9 @@ void __init hyperv_init(void)
>  	if (!hv_vp_index)
>  		return;
> 
> +	for (i = 0; i < num_possible_cpus(); i++)
> +		hv_vp_index[i] = -1;
> +
>  	hv_vp_assist_page = kcalloc(num_possible_cpus(),
>  				    sizeof(*hv_vp_assist_page), GFP_KERNEL);
>  	if (!hv_vp_assist_page) {
> diff --git a/arch/x86/include/asm/mshyperv.h
> b/arch/x86/include/asm/mshyperv.h
> index 81e768b8d9eb..299de3dcc319 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -285,6 +285,8 @@ static inline int cpumask_to_vpset(struct hv_vpset
> *vpset,
>  	 */
>  	for_each_cpu(cpu, cpus) {
>  		vcpu = hv_cpu_number_to_vp_number(cpu);
> +		if (vcpu == -1)
> +			return -1;
>  		vcpu_bank = vcpu / 64;
>  		vcpu_offset = vcpu % 64;
>  		__set_bit(vcpu_offset, (unsigned long *)
> --
> 2.17.1