linux-kernel - Re: [PATCH v2 4/5] arm64: Use __tlbi

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Date:   Fri, 6 Jan 2017 10:51:53 -0500
From:   Christopher Covington <cov@...eaurora.org>
To:     Mark Rutland <mark.rutland@....com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Christoffer Dall <christoffer.dall@...aro.org>,
        Marc Zyngier <marc.zyngier@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>, kvm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org, shankerd@...eaurora.org,
        timur@...eaurora.org
Subject: Re: [PATCH v2 4/5] arm64: Use __tlbi_dsb() macros in KVM code

On 01/03/2017 10:57 AM, Mark Rutland wrote:
> On Thu, Dec 29, 2016 at 05:43:34PM -0500, Christopher Covington wrote:
>> Refactor the KVM code to use the newly introduced __tlbi_dsb macros, which
>> will allow an errata workaround that repeats tlbi dsb sequences to only
>> change one location. This is not intended to change the generated assembly
>> and comparing before and after vmlinux objdump shows no functional changes.

@@ -32,7 +33,7 @@ void __hyp_text __kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa)
 	 * whole of Stage-1. Weep...
 	 */
 	ipa >>= 12;
-	asm volatile("tlbi ipas2e1is, %0" : : "r" (ipa));
+	__tlbi_dsb(ipas2e1is, ish, ipa);
 
 	/*
 	 * We have to ensure completion of the invalidation at Stage-2,

>> @@ -40,9 +41,7 @@ void __hyp_text __kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa)
>>  	 * complete (S1 + S2) walk based on the old Stage-2 mapping if
>>  	 * the Stage-1 invalidation happened first.
>>  	 */
>> -	dsb(ish);
> 
> Looks like this got accidentally removed. AFAICT it is still necessary.

Not removed, just hoisted above the comment block to the previous patch hunk.

>> -	asm volatile("tlbi vmalle1is" : : );
>> -	dsb(ish);
>> +	__tlbi_dsb(vmalle1is, ish);
>>  	isb();

Thanks,
Cov

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