From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Andrew Cooper <Andrew.Cooper3@citrix.com>,
Kai Huang <kai.huang@intel.com>, Chao Gao <chao.gao@intel.com>
Subject: Re: [PATCH v4 14/19] KVM: SVM: Check that the current CPU supports SVM in kvm_is_svm_supported()
Date: Mon, 24 Jul 2023 15:29:34 -0700 [thread overview]
Message-ID: <ZL77Tt42+ZI2BAv5@google.com> (raw)
In-Reply-To: <20230721201859.2307736-15-seanjc@google.com>
Hi Sean,
On Fri, Jul 21, 2023 at 01:18:54PM -0700, Sean Christopherson wrote:
> +static bool kvm_is_svm_supported(void)
> +{
> + bool supported;
> +
> + migrate_disable();
> + supported = __kvm_is_svm_supported();
> + migrate_enable();
I am typically very wary of the constructs like this, as the value
returned is obsolete the moment migrate_enable() happens. Is value of
"svm was supported at some time in the past but may or may not be
supported right now" useful and if it is then could you add comment why?
Thanks.
--
Dmitry
next prev parent reply other threads:[~2023-07-24 22:29 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-21 20:18 [PATCH v4 00/19] x86/reboot: KVM: Clean up "emergency" virt code Sean Christopherson
2023-07-21 20:18 ` [PATCH v4 01/19] x86/reboot: VMCLEAR active VMCSes before emergency reboot Sean Christopherson
2023-07-21 20:18 ` [PATCH v4 02/19] x86/reboot: Harden virtualization hooks for " Sean Christopherson
2023-07-21 20:18 ` [PATCH v4 03/19] x86/reboot: KVM: Handle VMXOFF in KVM's reboot callback Sean Christopherson
2023-07-24 23:57 ` Huang, Kai
2023-07-21 20:18 ` [PATCH v4 04/19] x86/reboot: KVM: Disable SVM during reboot via virt/KVM " Sean Christopherson
2023-07-21 20:18 ` [PATCH v4 05/19] x86/reboot: Assert that IRQs are disabled when turning off virtualization Sean Christopherson
2023-07-24 21:19 ` Peter Zijlstra
2023-07-24 21:41 ` Sean Christopherson
2023-07-21 20:18 ` [PATCH v4 06/19] x86/reboot: Hoist "disable virt" helpers above "emergency reboot" path Sean Christopherson
2023-07-21 20:18 ` [PATCH v4 07/19] x86/reboot: Disable virtualization during reboot iff callback is registered Sean Christopherson
2023-07-24 23:57 ` Huang, Kai
2023-07-21 20:18 ` [PATCH v4 08/19] x86/reboot: Expose VMCS crash hooks if and only if KVM_{INTEL,AMD} is enabled Sean Christopherson
2023-07-21 20:18 ` [PATCH v4 09/19] x86/virt: KVM: Open code cpu_has_vmx() in KVM VMX Sean Christopherson
2023-07-21 20:18 ` [PATCH v4 10/19] x86/virt: KVM: Move VMXOFF helpers into " Sean Christopherson
2023-07-28 9:08 ` Xu Yilun
2023-07-28 9:43 ` Huang, Kai
2023-07-21 20:18 ` [PATCH v4 11/19] KVM: SVM: Make KVM_AMD depend on CPU_SUP_AMD or CPU_SUP_HYGON Sean Christopherson
2023-07-21 20:18 ` [PATCH v4 12/19] x86/virt: Drop unnecessary check on extended CPUID level in cpu_has_svm() Sean Christopherson
2023-07-21 20:18 ` [PATCH v4 13/19] x86/virt: KVM: Open code cpu_has_svm() into kvm_is_svm_supported() Sean Christopherson
2023-07-21 20:18 ` [PATCH v4 14/19] KVM: SVM: Check that the current CPU supports SVM in kvm_is_svm_supported() Sean Christopherson
2023-07-24 21:21 ` Peter Zijlstra
2023-07-24 21:40 ` Sean Christopherson
2023-07-25 9:16 ` Peter Zijlstra
2023-07-27 16:39 ` Sean Christopherson
2023-07-24 22:29 ` Dmitry Torokhov [this message]
2023-07-24 23:53 ` Sean Christopherson
2023-07-21 20:18 ` [PATCH v4 15/19] KVM: VMX: Ensure CPU is stable when probing basic VMX support Sean Christopherson
2023-07-21 20:18 ` [PATCH v4 16/19] x86/virt: KVM: Move "disable SVM" helper into KVM SVM Sean Christopherson
2023-07-21 20:18 ` [PATCH v4 17/19] KVM: x86: Force kvm_rebooting=true during emergency reboot/crash Sean Christopherson
2023-07-21 20:18 ` [PATCH v4 18/19] KVM: SVM: Use "standard" stgi() helper when disabling SVM Sean Christopherson
2023-07-21 20:18 ` [PATCH v4 19/19] KVM: VMX: Skip VMCLEAR logic during emergency reboots if CR4.VMXE=0 Sean Christopherson
2023-07-25 3:51 ` Huang, Kai
2023-07-25 18:15 ` Sean Christopherson
2023-07-25 22:20 ` Huang, Kai
2023-08-04 0:40 ` [PATCH v4 00/19] x86/reboot: KVM: Clean up "emergency" virt code Sean Christopherson
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