From: Sean Christopherson <seanjc@google.com>
To: Zhao Liu <zhao1.liu@intel.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>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Shan Kang <shan.kang@intel.com>, Kai Huang <kai.huang@intel.com>,
Xin Li <xin3.li@intel.com>
Subject: Re: [PATCH v6 8/9] KVM: VMX: Open code VMX preemption timer rate mask in its accessor
Date: Fri, 15 Mar 2024 10:54:14 -0700 [thread overview]
Message-ID: <ZfSLRrf1CtJEGZw2@google.com> (raw)
In-Reply-To: <ZfRtSKcXTI/lAQxE@intel.com>
On Fri, Mar 15, 2024, Zhao Liu wrote:
> On Fri, Mar 08, 2024 at 05:27:24PM -0800, Sean Christopherson wrote:
> > Use vmx_misc_preemption_timer_rate() to get the rate in hardware_setup(),
> > and open code the rate's bitmask in vmx_misc_preemption_timer_rate() so
> > that the function looks like all the helpers that grab values from
> > VMX_BASIC and VMX_MISC MSR values.
...
> > -#define VMX_MISC_PREEMPTION_TIMER_RATE_MASK GENMASK_ULL(4, 0)
> > #define VMX_MISC_SAVE_EFER_LMA BIT_ULL(5)
> > #define VMX_MISC_ACTIVITY_HLT BIT_ULL(6)
> > #define VMX_MISC_ACTIVITY_SHUTDOWN BIT_ULL(7)
> > @@ -162,7 +161,7 @@ static inline u32 vmx_basic_vmcs_mem_type(u64 vmx_basic)
> >
> > static inline int vmx_misc_preemption_timer_rate(u64 vmx_misc)
> > {
> > - return vmx_misc & VMX_MISC_PREEMPTION_TIMER_RATE_MASK;
> > + return vmx_misc & GENMASK_ULL(4, 0);
> > }
>
> I feel keeping VMX_MISC_PREEMPTION_TIMER_RATE_MASK is clearer than
> GENMASK_ULL(4, 0), and the former improves code readability.
>
> May not need to drop VMX_MISC_PREEMPTION_TIMER_RATE_MASK?
I don't necessarily disagree, but in this case I value consistency over one
individual case. As called out in the changelog, the motivation is to make
vmx_misc_preemption_timer_rate() look like all the surrounding helpers.
_If_ we want to preserve the mask, then we should add #defines for vmx_misc_cr3_count(),
vmx_misc_max_msr(), etc.
I don't have a super strong preference, though I think my vote would be to not
add the masks and go with this patch. These helpers are intended to be the _only_
way to access the fields, i.e. they effectively _are_ the mask macros, just in
function form.
next prev parent reply other threads:[~2024-03-15 17:54 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-09 1:27 [PATCH v6 0/9] x86/cpu: KVM: Clean up PAT and VMX macros Sean Christopherson
2024-03-09 1:27 ` [PATCH v6 1/9] x86/cpu: KVM: Add common defines for architectural memory types (PAT, MTRRs, etc.) Sean Christopherson
2024-03-27 11:13 ` Huang, Kai
2024-04-03 18:57 ` Sean Christopherson
2024-04-03 21:17 ` Huang, Kai
2024-04-03 21:42 ` Sean Christopherson
2024-03-09 1:27 ` [PATCH v6 2/9] x86/cpu: KVM: Move macro to encode PAT value to common header Sean Christopherson
2024-03-27 11:21 ` Huang, Kai
2024-04-01 5:28 ` Xiaoyao Li
2024-04-03 21:03 ` Huang, Kai
2024-03-09 1:27 ` [PATCH v6 3/9] KVM: x86: Stuff vCPU's PAT with default value at RESET, not creation Sean Christopherson
2024-03-27 11:22 ` Huang, Kai
2024-04-01 6:00 ` Xiaoyao Li
2024-03-09 1:27 ` [PATCH v6 4/9] KVM: VMX: Move MSR_IA32_VMX_BASIC bit defines to asm/vmx.h Sean Christopherson
2024-03-15 15:13 ` Zhao Liu
2024-03-27 10:37 ` Huang, Kai
2024-04-01 6:13 ` Xiaoyao Li
2024-04-02 5:01 ` Li, Xin3
2024-04-02 14:28 ` Sean Christopherson
2024-03-09 1:27 ` [PATCH v6 5/9] KVM: VMX: Track CPU's MSR_IA32_VMX_BASIC as a single 64-bit value Sean Christopherson
2024-03-15 15:26 ` Zhao Liu
2024-03-27 10:38 ` Huang, Kai
2024-04-01 6:27 ` Xiaoyao Li
2024-03-09 1:27 ` [PATCH v6 6/9] KVM: nVMX: Use macros and #defines in vmx_restore_vmx_basic() Sean Christopherson
2024-03-15 15:30 ` Zhao Liu
2024-03-27 10:53 ` Huang, Kai
2024-04-01 7:00 ` Xiaoyao Li
2024-03-09 1:27 ` [PATCH v6 7/9] KVM VMX: Move MSR_IA32_VMX_MISC bit defines to asm/vmx.h Sean Christopherson
2024-03-15 15:43 ` Zhao Liu
2024-03-27 10:55 ` Huang, Kai
2024-03-09 1:27 ` [PATCH v6 8/9] KVM: VMX: Open code VMX preemption timer rate mask in its accessor Sean Christopherson
2024-03-15 15:46 ` Zhao Liu
2024-03-15 17:54 ` Sean Christopherson [this message]
2024-04-01 7:07 ` Xiaoyao Li
2024-04-02 22:06 ` Sean Christopherson
2024-04-24 20:06 ` Sean Christopherson
2024-04-25 10:05 ` Huang, Kai
2024-04-25 14:42 ` Sean Christopherson
2024-04-25 21:44 ` Huang, Kai
2024-04-25 14:18 ` Xiaoyao Li
2024-03-27 10:59 ` Huang, Kai
2024-03-09 1:27 ` [PATCH v6 9/9] KVM: nVMX: Use macros and #defines in vmx_restore_vmx_misc() Sean Christopherson
2024-03-15 15:52 ` Zhao Liu
2024-03-27 11:02 ` Huang, Kai
2024-04-01 7:09 ` Xiaoyao Li
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