From: Yuan Yao <yuan.yao@linux.intel.com>
To: isaku.yamahata@intel.com
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Marc Zyngier <maz@kernel.org>, Will Deacon <will@kernel.org>,
isaku.yamahata@gmail.com, Kai Huang <kai.huang@intel.com>,
Chao Gao <chao.gao@intel.com>,
Atish Patra <atishp@atishpatra.org>,
Shaokun Zhang <zhangshaokun@hisilicon.com>,
Qi Liu <liuqi115@huawei.com>, John Garry <john.garry@huawei.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Huang Ying <ying.huang@intel.com>,
Huacai Chen <chenhuacai@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH v3 16/22] KVM: kvm_arch.c: Remove a global variable, hardware_enable_failed
Date: Wed, 7 Sep 2022 13:56:57 +0800 [thread overview]
Message-ID: <20220907055657.y7dcseig2qvjue6t@yy-desk-7060> (raw)
In-Reply-To: <91715ddc16f001bf2b76f68b57ebd59092b40591.1662084396.git.isaku.yamahata@intel.com>
On Thu, Sep 01, 2022 at 07:17:51PM -0700, isaku.yamahata@intel.com wrote:
> From: Isaku Yamahata <isaku.yamahata@intel.com>
>
> A global variable hardware_enable_failed in kvm_arch.c is used only by
> kvm_arch_add_vm() and hardware_enable(). It doesn't have to be a global
> variable. Make it function local.
>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> ---
> virt/kvm/kvm_arch.c | 49 +++++++++++++++++++++------------------------
> 1 file changed, 23 insertions(+), 26 deletions(-)
>
> diff --git a/virt/kvm/kvm_arch.c b/virt/kvm/kvm_arch.c
> index de39d0127584..f7dcde842eb5 100644
> --- a/virt/kvm/kvm_arch.c
> +++ b/virt/kvm/kvm_arch.c
> @@ -13,14 +13,13 @@
> #include <linux/kvm_host.h>
>
> static cpumask_t cpus_hardware_enabled = CPU_MASK_NONE;
> -static atomic_t hardware_enable_failed;
>
> __weak int kvm_arch_post_init_vm(struct kvm *kvm)
> {
> return 0;
> }
>
> -static void hardware_enable(void *caller_name)
> +static int __hardware_enable(void *caller_name)
> {
> int cpu = raw_smp_processor_id();
> int r;
> @@ -28,18 +27,22 @@ static void hardware_enable(void *caller_name)
> WARN_ON_ONCE(preemptible());
>
> if (cpumask_test_cpu(cpu, &cpus_hardware_enabled))
> - return;
> -
> - cpumask_set_cpu(cpu, &cpus_hardware_enabled);
> -
> + return 0;
> r = kvm_arch_hardware_enable();
> -
> - if (r) {
> - cpumask_clear_cpu(cpu, &cpus_hardware_enabled);
> - atomic_inc(&hardware_enable_failed);
> + if (r)
> pr_warn("kvm: enabling virtualization on CPU%d failed during %s()\n",
> cpu, (const char *)caller_name);
> - }
> + else
> + cpumask_set_cpu(cpu, &cpus_hardware_enabled);
> + return r;
> +}
> +
> +static void hardware_enable(void *arg)
> +{
> + atomic_t *failed = arg;
> +
> + if (__hardware_enable((void *)__func__))
> + atomic_inc(failed);
> }
A side effect: The actual caller_name information introduced in Patch
3 for hardware_enable() is lost. I tend to keep the information, but
depends on you and other guys. :-)
>
> static void hardware_disable(void *junk)
> @@ -65,15 +68,16 @@ __weak void kvm_arch_pre_hardware_unsetup(void)
> */
> __weak int kvm_arch_add_vm(struct kvm *kvm, int usage_count)
> {
> + atomic_t failed;
> int r = 0;
>
> if (usage_count != 1)
> return 0;
>
> - atomic_set(&hardware_enable_failed, 0);
> - on_each_cpu(hardware_enable, (void *)__func__, 1);
> + atomic_set(&failed, 0);
> + on_each_cpu(hardware_enable, &failed, 1);
>
> - if (atomic_read(&hardware_enable_failed)) {
> + if (atomic_read(&failed)) {
> r = -EBUSY;
> goto err;
> }
> @@ -96,27 +100,20 @@ __weak int kvm_arch_del_vm(int usage_count)
>
> __weak int kvm_arch_online_cpu(unsigned int cpu, int usage_count)
> {
> - int ret = 0;
> + int ret;
>
> ret = kvm_arch_check_processor_compat();
> if (ret)
> return ret;
>
> + if (!usage_count)
> + return 0;
> /*
> * Abort the CPU online process if hardware virtualization cannot
> * be enabled. Otherwise running VMs would encounter unrecoverable
> * errors when scheduled to this CPU.
> */
> - if (usage_count) {
> - WARN_ON_ONCE(atomic_read(&hardware_enable_failed));
> -
> - hardware_enable((void *)__func__);
> - if (atomic_read(&hardware_enable_failed)) {
> - atomic_set(&hardware_enable_failed, 0);
> - ret = -EIO;
> - }
> - }
> - return ret;
> + return __hardware_enable((void *)__func__);
> }
>
> __weak int kvm_arch_offline_cpu(unsigned int cpu, int usage_count)
> @@ -149,5 +146,5 @@ __weak void kvm_arch_resume(int usage_count)
> return; /* FIXME: disable KVM */
>
> if (usage_count)
> - hardware_enable((void *)__func__);
> + (void)__hardware_enable((void *)__func__);
> }
> --
> 2.25.1
>
next prev parent reply other threads:[~2022-09-07 5:57 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-02 2:17 [PATCH v3 00/22] KVM: hardware enable/disable reorganize isaku.yamahata
2022-09-02 2:17 ` [PATCH v3 01/22] KVM: x86: Drop kvm_user_return_msr_cpu_online() isaku.yamahata
2022-09-05 1:59 ` Chao Gao
2022-09-05 5:30 ` Yuan Yao
2022-09-02 2:17 ` [PATCH v3 02/22] KVM: x86: Use this_cpu_ptr() instead of per_cpu_ptr(smp_processor_id()) isaku.yamahata
2022-09-05 5:35 ` Yuan Yao
2022-09-02 2:17 ` [PATCH v3 03/22] KVM: x86: Move check_processor_compatibility from init ops to runtime ops isaku.yamahata
2022-09-05 5:42 ` Yuan Yao
2022-09-02 2:17 ` [PATCH v3 04/22] Partially revert "KVM: Pass kvm_init()'s opaque param to additional arch funcs" isaku.yamahata
2022-09-05 5:48 ` Yuan Yao
2022-09-02 2:17 ` [PATCH v3 05/22] KVM: Provide more information in kernel log if hardware enabling fails isaku.yamahata
2022-09-05 5:56 ` Yuan Yao
2022-09-02 2:17 ` [PATCH v3 06/22] KVM: arm64: Simplify the CPUHP logic isaku.yamahata
2022-09-05 7:05 ` Yuan Yao
2022-09-05 9:29 ` Marc Zyngier
2022-09-05 12:39 ` Marc Zyngier
2022-09-07 15:12 ` Isaku Yamahata
2022-09-02 2:17 ` [PATCH v3 07/22] KVM: Rename and move CPUHP_AP_KVM_STARTING to ONLINE section isaku.yamahata
2022-09-05 7:49 ` Yuan Yao
2022-09-02 2:17 ` [PATCH v3 08/22] KVM: Do compatibility checks on hotplugged CPUs isaku.yamahata
2022-09-06 1:25 ` Yuan Yao
2022-09-02 2:17 ` [PATCH v3 09/22] KVM: Do processor compatibility check on resume isaku.yamahata
2022-09-05 8:40 ` Yuan Yao
2022-09-05 9:27 ` Yuan Yao
2022-09-08 18:21 ` Isaku Yamahata
2022-09-02 2:17 ` [PATCH v3 10/22] KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock isaku.yamahata
2022-09-06 2:46 ` Yuan Yao
2022-09-06 6:32 ` Marc Zyngier
2022-09-06 21:44 ` Isaku Yamahata
2022-09-08 18:24 ` Isaku Yamahata
2022-09-02 2:17 ` [PATCH v3 11/22] KVM: Add arch hooks for PM events with empty stub isaku.yamahata
2022-09-06 6:25 ` Yuan Yao
2022-09-08 19:11 ` Isaku Yamahata
2022-09-02 2:17 ` [PATCH v3 12/22] KVM: x86: Move TSC fixup logic to KVM arch resume callback isaku.yamahata
2022-09-02 2:17 ` [PATCH v3 13/22] KVM: Add arch hook when VM is added/deleted isaku.yamahata
2022-09-02 2:17 ` [PATCH v3 14/22] KVM: Move out KVM arch PM hooks and hardware enable/disable logic isaku.yamahata
2022-09-06 7:43 ` Yuan Yao
2022-09-08 19:15 ` Isaku Yamahata
2022-09-02 2:17 ` [PATCH v3 15/22] KVM: kvm_arch.c: Remove _nolock post fix isaku.yamahata
2022-09-02 2:17 ` [PATCH v3 16/22] KVM: kvm_arch.c: Remove a global variable, hardware_enable_failed isaku.yamahata
2022-09-07 5:56 ` Yuan Yao [this message]
2022-09-08 22:51 ` Isaku Yamahata
2022-09-02 2:17 ` [PATCH v3 17/22] KVM: x86: Duplicate arch callbacks related to pm events isaku.yamahata
2022-09-02 2:17 ` [PATCH v3 18/22] KVM: Eliminate kvm_arch_post_init_vm() isaku.yamahata
2022-09-02 2:17 ` [PATCH v3 19/22] KVM: x86: Delete kvm_arch_hardware_enable/disable() isaku.yamahata
2022-09-02 2:17 ` [PATCH v3 20/22] KVM: Add config to not compile kvm_arch.c isaku.yamahata
2022-09-02 2:17 ` [PATCH v3 21/22] RFC: KVM: x86: Remove cpus_hardware_enabled and related sanity check isaku.yamahata
2022-09-02 2:17 ` [PATCH v3 22/22] RFC: KVM: " isaku.yamahata
2022-09-05 15:38 ` [PATCH v3 00/22] KVM: hardware enable/disable reorganize Marc Zyngier
2022-09-06 22:25 ` Isaku Yamahata
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