linux-kernel - Re: [PATCH v3 05/11] kvm: arm64: Remove hyp_adr/ldr_this

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Date:   Mon, 21 Sep 2020 15:53:20 +0100
From:   David Brazdil <dbrazdil@...gle.com>
To:     Will Deacon <will@...nel.org>
Cc:     kvmarm@...ts.cs.columbia.edu,
        Catalin Marinas <catalin.marinas@....com>,
        Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Dennis Zhou <dennis@...nel.org>, Tejun Heo <tj@...nel.org>,
        Christoph Lameter <cl@...ux.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel-team@...roid.com, Andrew Scull <ascull@...gle.com>
Subject: Re: [PATCH v3 05/11] kvm: arm64: Remove hyp_adr/ldr_this_cpu

Hi Will,

> Cosmetic, but I think it would be cleaner just to define two variants of the
> macro here:
> 
> #if defined(__KVM_NVHE_HYPERVISOR__) || defined(__KVM_VHE_HYPERVISOR__)
> 	.macro  this_cpu_offset, dst
> 	mrs     \dst, tpidr_el2
> 	.endm
> #else
> 	.macro  this_cpu_offset, dst
> alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
> 	mrs     \dst, tpidr_el1
> alternative_else
> 	mrs     \dst, tpidr_el2
> alternative_endif
> 	.endm
> #endif

Sure.

> (and should we have a shorthand __HYPERVISOR define to avoid the NVHE || VHE
> logic?)

Happy to add this but let's agree on the details.
 * name: just __HYPERVISOR or __KVM_HYPERVISOR__?
 * defined where? I'm wary of defining it in a header file because then sombody
   will forget to add it and 'ifdef HYP' will be skipped. So I'd put this as
   another '-D__HYPERVISOR' in the build rules. Do you agree?

David