public inbox for linux-kernel@vger.kernel.org
 help / color / mirror / Atom feed
From: Sean Christopherson <seanjc@google.com>
To: 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, Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>
Cc: 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: [PATCH v2 12/18] x86/virt: Drop unnecessary check on extended CPUID level in cpu_has_svm()
Date: Fri, 10 Mar 2023 13:42:26 -0800	[thread overview]
Message-ID: <20230310214232.806108-13-seanjc@google.com> (raw)
In-Reply-To: <20230310214232.806108-1-seanjc@google.com>

Drop the explicit check on the extended CPUID level in cpu_has_svm(), the
kernel's cached CPUID info will leave the entire SVM leaf unset if said
leaf is not supported by hardware.  Prior to using cached information,
the check was needed to avoid false positives due to Intel's rather crazy
CPUID behavior of returning the values of the maximum supported leaf if
the specified leaf is unsupported.

Fixes: 682a8108872f ("x86/kvm/svm: Simplify cpu_has_svm()")
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/include/asm/virtext.h | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/arch/x86/include/asm/virtext.h b/arch/x86/include/asm/virtext.h
index a27801f2bc71..be50c414efe4 100644
--- a/arch/x86/include/asm/virtext.h
+++ b/arch/x86/include/asm/virtext.h
@@ -39,12 +39,6 @@ static inline int cpu_has_svm(const char **msg)
 		return 0;
 	}
 
-	if (boot_cpu_data.extended_cpuid_level < SVM_CPUID_FUNC) {
-		if (msg)
-			*msg = "can't execute cpuid_8000000a";
-		return 0;
-	}
-
 	if (!boot_cpu_has(X86_FEATURE_SVM)) {
 		if (msg)
 			*msg = "svm not available";
-- 
2.40.0.rc1.284.g88254d51c5-goog


  parent reply	other threads:[~2023-03-10 21:44 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-10 21:42 [PATCH v2 00/18] x86/reboot: KVM: Clean up "emergency" virt code Sean Christopherson
2023-03-10 21:42 ` [PATCH v2 01/18] x86/reboot: VMCLEAR active VMCSes before emergency reboot Sean Christopherson
2023-03-10 21:42 ` [PATCH v2 02/18] x86/reboot: Expose VMCS crash hooks if and only if KVM_INTEL is enabled Sean Christopherson
2023-03-13  0:31   ` Huang, Kai
2023-03-13 18:31     ` Sean Christopherson
2023-03-14  1:19       ` Huang, Kai
2023-03-10 21:42 ` [PATCH v2 03/18] x86/reboot: Harden virtualization hooks for emergency reboot Sean Christopherson
2023-03-13  8:26   ` Chao Gao
2023-03-13 17:08     ` Sean Christopherson
2023-03-10 21:42 ` [PATCH v2 04/18] x86/reboot: KVM: Handle VMXOFF in KVM's reboot callback Sean Christopherson
2023-03-10 21:42 ` [PATCH v2 05/18] x86/reboot: KVM: Disable SVM during reboot via virt/KVM " Sean Christopherson
2023-03-13  0:52   ` Huang, Kai
2023-03-13 17:18     ` Sean Christopherson
2023-03-14  0:42       ` Huang, Kai
2023-03-15  0:47         ` Sean Christopherson
2023-03-15  1:30           ` Huang, Kai
2023-03-10 21:42 ` [PATCH v2 06/18] x86/reboot: Hoist "disable virt" helpers above "emergency reboot" path Sean Christopherson
2023-03-10 21:42 ` [PATCH v2 07/18] x86/reboot: Disable virtualization during reboot iff callback is registered Sean Christopherson
2023-03-13  0:54   ` Huang, Kai
2023-03-13 18:40     ` Sean Christopherson
2023-03-14  0:50       ` Huang, Kai
2023-03-10 21:42 ` [PATCH v2 08/18] x86/reboot: Assert that IRQs are disabled when turning off virtualization Sean Christopherson
2023-03-10 21:42 ` [PATCH v2 09/18] x86/virt: KVM: Open code cpu_has_vmx() in KVM VMX Sean Christopherson
2023-03-10 21:42 ` [PATCH v2 10/18] x86/virt: KVM: Move VMXOFF helpers into " Sean Christopherson
2023-03-10 21:42 ` [PATCH v2 11/18] KVM: SVM: Make KVM_AMD depend on CPU_SUP_AMD or CPU_SUP_HYGON Sean Christopherson
2023-03-10 21:42 ` Sean Christopherson [this message]
2023-03-10 21:42 ` [PATCH v2 13/18] x86/virt: KVM: Open code cpu_has_svm() into kvm_is_svm_supported() Sean Christopherson
2023-03-10 21:42 ` [PATCH v2 14/18] KVM: SVM: Check that the current CPU supports SVM in kvm_is_svm_supported() Sean Christopherson
2023-03-13  2:47   ` Huang, Kai
2023-03-13 17:29     ` Sean Christopherson
2023-03-14  0:17       ` Huang, Kai
2023-03-10 21:42 ` [PATCH v2 15/18] KVM: VMX: Ensure CPU is stable when probing basic VMX support Sean Christopherson
2023-03-10 21:42 ` [PATCH v2 16/18] x86/virt: KVM: Move "disable SVM" helper into KVM SVM Sean Christopherson
2023-03-10 21:42 ` [PATCH v2 17/18] KVM: x86: Force kvm_rebooting=true during emergency reboot/crash Sean Christopherson
2023-03-10 21:42 ` [PATCH v2 18/18] KVM: SVM: Use "standard" stgi() helper when disabling SVM Sean Christopherson

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20230310214232.806108-13-seanjc@google.com \
    --to=seanjc@google.com \
    --cc=Andrew.Cooper3@citrix.com \
    --cc=bp@alien8.de \
    --cc=chao.gao@intel.com \
    --cc=dave.hansen@linux.intel.com \
    --cc=kai.huang@intel.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=pbonzini@redhat.com \
    --cc=tglx@linutronix.de \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox