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From: Quentin Perret <qperret@google.com>
To: Marc Zyngier <maz@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Will Deacon <will@kernel.org>,
	kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH 01/15] arm64: kvm: Unify users of HVC instruction
Date: Thu, 7 May 2020 15:36:33 +0100
Message-ID: <20200507143633.GA169263@google.com> (raw)
In-Reply-To: <878si3j13w.wl-maz@kernel.org>

On Thursday 07 May 2020 at 15:01:07 (+0100), Marc Zyngier wrote:
> >  /*
> > - * u64 __kvm_call_hyp(void *hypfn, ...);
> > + * u64 __kvm_call_hyp(unsigned long arg, ...);
> >   *
> >   * This is not really a variadic function in the classic C-way and care must
> >   * be taken when calling this to ensure parameters are passed in registers
> >   * only, since the stack will change between the caller and the callee.
> > - *
> > - * Call the function with the first argument containing a pointer to the
> > - * function you wish to call in Hyp mode, and subsequent arguments will be
> > - * passed as x0, x1, and x2 (a maximum of 3 arguments in addition to the
> > - * function pointer can be passed).  The function being called must be mapped
> > - * in Hyp mode (see init_hyp_mode in arch/arm/kvm/arm.c).  Return values are
> > - * passed in x0.
> > - *
> > - * A function pointer with a value less than 0xfff has a special meaning,
> > - * and is used to implement hyp stubs in the same way as in
> > - * arch/arm64/kernel/hyp_stub.S.
> 
> I don't think any of this becomes obsolete with this patch (apart from
> the reference to 32bit), and only changes with patch #2. Or am I
> misunderstanding something?

Nope, I think you're right. To be fair, this patch has changed quite
a bit since the first version (which did change that comment a little
later IIRC), but David has done all the hard work on top so I'll let
him answer that one.

And David, feel free to take the authorship for this patch -- I barely
recognize it (for the better), so it's more than fair if you get the
credit :)

Thanks,
Quentin
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Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-30 14:48 [PATCH 00/15] Split off nVHE hyp code David Brazdil
2020-04-30 14:48 ` [PATCH 01/15] arm64: kvm: Unify users of HVC instruction David Brazdil
2020-05-07 14:01   ` Marc Zyngier
2020-05-07 14:36     ` Quentin Perret [this message]
2020-05-13 10:30       ` David Brazdil
2020-04-30 14:48 ` [PATCH 02/15] arm64: kvm: Formalize host-hyp hypcall ABI David Brazdil
2020-05-07 13:10   ` Marc Zyngier
2020-05-07 13:33     ` Quentin Perret
2020-05-10 10:16       ` Marc Zyngier
2020-05-13 10:48         ` David Brazdil
2020-04-30 14:48 ` [PATCH 03/15] arm64: kvm: Fix symbol dependency in __hyp_call_panic_nvhe David Brazdil
2020-05-07 13:22   ` Marc Zyngier
2020-05-07 14:36     ` David Brazdil
2020-05-10 11:14       ` Marc Zyngier
2020-04-30 14:48 ` [PATCH 04/15] arm64: kvm: Add build rules for separate nVHE object files David Brazdil
2020-05-07 13:46   ` Marc Zyngier
2020-04-30 14:48 ` [PATCH 05/15] arm64: kvm: Build hyp-entry.S separately for VHE/nVHE David Brazdil
2020-05-07 15:07   ` Marc Zyngier
2020-05-07 15:15     ` Marc Zyngier
2020-04-30 14:48 ` [PATCH 06/15] arm64: kvm: Move __smccc_workaround_1_smc to .rodata David Brazdil
2020-05-11 10:04   ` Marc Zyngier
2020-05-11 10:29     ` Will Deacon
2020-04-30 14:48 ` [PATCH 07/15] arm64: kvm: Split hyp/tlb.c to VHE/nVHE David Brazdil
2020-04-30 14:48 ` [PATCH 08/15] arm64: kvm: Split hyp/switch.c " David Brazdil
2020-04-30 14:48 ` [PATCH 09/15] arm64: kvm: Split hyp/debug-sr.c " David Brazdil
2020-04-30 14:48 ` [PATCH 10/15] arm64: kvm: Split hyp/sysreg-sr.c " David Brazdil
2020-04-30 14:48 ` [PATCH 11/15] arm64: kvm: Split hyp/timer-sr.c " David Brazdil
2020-04-30 14:48 ` [PATCH 12/15] arm64: kvm: Compile remaining hyp/ files for both VHE/nVHE David Brazdil
2020-04-30 14:48 ` [PATCH 13/15] arm64: kvm: Add comments around __hyp_text_ symbol aliases David Brazdil
2020-04-30 14:48 ` [PATCH 14/15] arm64: kvm: Remove __hyp_text macro, use build rules instead David Brazdil
2020-04-30 14:48 ` [PATCH 15/15] arm64: kvm: Lift instrumentation restrictions on VHE David Brazdil
2020-04-30 17:53 ` [PATCH 00/15] Split off nVHE hyp code Marc Zyngier
2020-04-30 18:57   ` David Brazdil

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