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From: Marc Zyngier <maz@kernel.org>
To: Alexandru Elisei <alexandru.elisei@arm.com>
Cc: kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 3/5] KVM: arm64: Rename __vcpu_sys_reg -> vcpu_sys_reg
Date: Wed, 14 Jul 2021 11:23:52 +0100	[thread overview]
Message-ID: <87k0lt6vnr.wl-maz@kernel.org> (raw)
In-Reply-To: <20210714095601.184854-4-alexandru.elisei@arm.com>

Hi Alex,

On Wed, 14 Jul 2021 10:55:59 +0100,
Alexandru Elisei <alexandru.elisei@arm.com> wrote:
> 
> There are two macros to access a specific system register from a known
> kvm_cpu_context: __ctxt_sys_reg(), which returns a pointer to the register,
> and ctxt_sys_reg(), which deferences the pointer returned by
> __ctxt_sys_reg().
> 
> __vcpu_sys_reg() serves a similar purpose, with the difference being that
> it takes a struct kvm_vcpu as a parameter. __vcpu_sys_reg(), although it
> looks like __ctxt_sys_reg(), it dereferences the pointer to the register,
> like ctxt_sys_reg() does, and indeed it is defined as an abstraction over
> ctxt_sys_reg().
> 
> Let's remove this naming inconsistency by renaming __vcpu_sys_reg() to
> vcpu_sys_reg(), to make it clear it behaves like ctxt_sys_reg(), and not
> like __ctxt_sys_reg().

I can't say I'm keen on this change.

The leading underscores really are there to outline that *this is
dangerous*, as you really need to know which context you are in.
Dropping the leading '__' may give the false impression that this is
safe, and not actually a primitive that requires careful thinking
before use.

ctxt_sys_reg() is, on the other hand, clearly something that acts
solely on memory because it takes a context structure, and not a
vcpu. At least that's what the 'ctxt' prefix is supposed to convey
(not very successfully, apparently).

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.
_______________________________________________
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kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Alexandru Elisei <alexandru.elisei@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, james.morse@arm.com,
	suzuki.poulose@arm.com
Subject: Re: [PATCH 3/5] KVM: arm64: Rename __vcpu_sys_reg -> vcpu_sys_reg
Date: Wed, 14 Jul 2021 11:23:52 +0100	[thread overview]
Message-ID: <87k0lt6vnr.wl-maz@kernel.org> (raw)
In-Reply-To: <20210714095601.184854-4-alexandru.elisei@arm.com>

Hi Alex,

On Wed, 14 Jul 2021 10:55:59 +0100,
Alexandru Elisei <alexandru.elisei@arm.com> wrote:
> 
> There are two macros to access a specific system register from a known
> kvm_cpu_context: __ctxt_sys_reg(), which returns a pointer to the register,
> and ctxt_sys_reg(), which deferences the pointer returned by
> __ctxt_sys_reg().
> 
> __vcpu_sys_reg() serves a similar purpose, with the difference being that
> it takes a struct kvm_vcpu as a parameter. __vcpu_sys_reg(), although it
> looks like __ctxt_sys_reg(), it dereferences the pointer to the register,
> like ctxt_sys_reg() does, and indeed it is defined as an abstraction over
> ctxt_sys_reg().
> 
> Let's remove this naming inconsistency by renaming __vcpu_sys_reg() to
> vcpu_sys_reg(), to make it clear it behaves like ctxt_sys_reg(), and not
> like __ctxt_sys_reg().

I can't say I'm keen on this change.

The leading underscores really are there to outline that *this is
dangerous*, as you really need to know which context you are in.
Dropping the leading '__' may give the false impression that this is
safe, and not actually a primitive that requires careful thinking
before use.

ctxt_sys_reg() is, on the other hand, clearly something that acts
solely on memory because it takes a context structure, and not a
vcpu. At least that's what the 'ctxt' prefix is supposed to convey
(not very successfully, apparently).

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2021-07-14 10:24 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-14  9:55 [PATCH 0/5] KVM: arm64: Cleanups and one optimization Alexandru Elisei
2021-07-14  9:55 ` Alexandru Elisei
2021-07-14  9:55 ` [PATCH 1/5] KVM: arm64: Move vcpu_has_feature() to asm/kvm_host.h Alexandru Elisei
2021-07-14  9:55   ` Alexandru Elisei
2021-07-14  9:55 ` [PATCH 2/5] KVM: arm64: Use vcpu_has_feature() to check the feature bits Alexandru Elisei
2021-07-14  9:55   ` Alexandru Elisei
2021-07-14  9:55 ` [PATCH 3/5] KVM: arm64: Rename __vcpu_sys_reg -> vcpu_sys_reg Alexandru Elisei
2021-07-14  9:55   ` Alexandru Elisei
2021-07-14 10:23   ` Marc Zyngier [this message]
2021-07-14 10:23     ` Marc Zyngier
2021-07-14 10:40     ` Alexandru Elisei
2021-07-14 10:40       ` Alexandru Elisei
2021-07-14  9:56 ` [PATCH 4/5] KVM: arm64: Add __vcpu_sys_reg() Alexandru Elisei
2021-07-14  9:56   ` Alexandru Elisei
2021-07-14  9:56 ` [PATCH 5/5] KVM: arm64: nVHE: Remove unneeded isb() when modifying PMSCR_EL1 Alexandru Elisei
2021-07-14  9:56   ` Alexandru Elisei
2021-07-14 18:20   ` Will Deacon
2021-07-14 18:20     ` Will Deacon
2021-07-15  9:31     ` Alexandru Elisei
2021-07-15  9:31       ` Alexandru Elisei

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