linux-kernel - Re: [RFC PATCH v7 01/37] KVM: lapic: Remove __apic_test_and_{set|clear}

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Message-ID: <8d1e6138-2d08-4207-8ece-d38366d9a27e@amd.com>
Date: Wed, 25 Jun 2025 06:48:53 +0530
From: Neeraj Upadhyay <Neeraj.Upadhyay@....com>
To: Borislav Petkov <bp@...en8.de>
Cc: linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
 dave.hansen@...ux.intel.com, Thomas.Lendacky@....com, nikunj@....com,
 Santosh.Shukla@....com, Vasant.Hegde@....com, Suravee.Suthikulpanit@....com,
 David.Kaplan@....com, x86@...nel.org, hpa@...or.com, peterz@...radead.org,
 seanjc@...gle.com, pbonzini@...hat.com, kvm@...r.kernel.org,
 kirill.shutemov@...ux.intel.com, huibo.wang@....com, naveen.rao@....com,
 francescolavra.fl@...il.com, tiala@...rosoft.com
Subject: Re: [RFC PATCH v7 01/37] KVM: lapic: Remove
 __apic_test_and_{set|clear}_vector()



On 6/23/2025 4:56 PM, Borislav Petkov wrote:
> On Tue, Jun 10, 2025 at 11:23:48PM +0530, Neeraj Upadhyay wrote:
>> Remove __apic_test_and_set_vector() and __apic_test_and_clear_vector(),
>> because the _only_ register that's safe to modify with a non-atomic
>> operation is ISR, because KVM isn't running the vCPU, i.e. hardware can't
>> service an IRQ or process an EOI for the relevant (virtual) APIC.
>>
>> No functional change intended.
>>
>> Suggested-by: Sean Christopherson <seanjc@...gle.com>
>> [Neeraj: Add "inline" for apic_vector_to_isr()]
>> Signed-off-by: Neeraj Upadhyay <Neeraj.Upadhyay@....com>
>> ---
>> Changes since v6:
>>
>>  - New change.
>>
>>  arch/x86/kvm/lapic.c | 19 +++++++------------
>>  1 file changed, 7 insertions(+), 12 deletions(-)
> 
> FWIW: LGTM.
> 
> :-)
> 

Thank you for the review!

- Neeraj