From: Will Deacon <will@kernel.org>
To: Marc Zyngier <maz@kernel.org>
Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org,
James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
qperret@google.com, kernel-team@android.com
Subject: Re: [PATCH 3/4] KVM: arm64: Rename SCTLR_ELx_FLAGS to SCTLR_EL2_FLAGS
Date: Wed, 10 Mar 2021 18:20:22 +0000 [thread overview]
Message-ID: <20210310182022.GA29969@willie-the-truck> (raw)
In-Reply-To: <87zgzagaqq.wl-maz@kernel.org>
On Wed, Mar 10, 2021 at 05:49:17PM +0000, Marc Zyngier wrote:
> On Wed, 10 Mar 2021 16:15:47 +0000,
> Will Deacon <will@kernel.org> wrote:
> > On Wed, Mar 10, 2021 at 04:05:17PM +0000, Marc Zyngier wrote:
> > > On Wed, 10 Mar 2021 15:46:26 +0000,
> > > Will Deacon <will@kernel.org> wrote:
> > > > On Wed, Mar 10, 2021 at 03:26:55PM +0000, Marc Zyngier wrote:
> > > > > diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
> > > > > index 4eb584ae13d9..7423f4d961a4 100644
> > > > > --- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S
> > > > > +++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
> > > > > @@ -122,7 +122,7 @@ alternative_else_nop_endif
> > > > > * as well as the EE bit on BE. Drop the A flag since the compiler
> > > > > * is allowed to generate unaligned accesses.
> > > > > */
> > > > > - mov_q x0, (SCTLR_EL2_RES1 | (SCTLR_ELx_FLAGS & ~SCTLR_ELx_A))
> > > > > + mov_q x0, (SCTLR_EL2_RES1 | (SCTLR_EL2_FLAGS & ~SCTLR_ELx_A))
> > > >
> > > > Can we just drop SCTLR_ELx_A from SCTLR_EL2_FLAGS instead of clearing it
> > > > here?
> > >
> > > Absolutely. That'd actually be an improvement.
> >
> > In fact, maybe just define INIT_SCTLR_EL2_MMU_ON to mirror what we do for
> > EL1 (i.e. including the RES1 bits) and then use that here?
>
> Like this?
>
> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
> index dfd4edbfe360..593b9bf91bbd 100644
> --- a/arch/arm64/include/asm/sysreg.h
> +++ b/arch/arm64/include/asm/sysreg.h
> @@ -579,9 +579,6 @@
> #define SCTLR_ELx_A (BIT(1))
> #define SCTLR_ELx_M (BIT(0))
>
> -#define SCTLR_ELx_FLAGS (SCTLR_ELx_M | SCTLR_ELx_A | SCTLR_ELx_C | \
> - SCTLR_ELx_SA | SCTLR_ELx_I | SCTLR_ELx_IESB)
> -
> /* SCTLR_EL2 specific flags. */
> #define SCTLR_EL2_RES1 ((BIT(4)) | (BIT(5)) | (BIT(11)) | (BIT(16)) | \
> (BIT(18)) | (BIT(22)) | (BIT(23)) | (BIT(28)) | \
> @@ -593,6 +590,10 @@
> #define ENDIAN_SET_EL2 0
> #endif
>
> +#define INIT_SCTLR_EL2_MMU_ON \
> + (SCTLR_ELx_M | SCTLR_ELx_C | SCTLR_ELx_SA | SCTLR_ELx_I | \
> + SCTLR_ELx_IESB | ENDIAN_SET_EL2 | SCTLR_EL2_RES1)
> +
> #define INIT_SCTLR_EL2_MMU_OFF \
> (SCTLR_EL2_RES1 | ENDIAN_SET_EL2)
>
> diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
> index 4eb584ae13d9..2e16b2098bbd 100644
> --- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S
> +++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
> @@ -117,13 +117,7 @@ alternative_else_nop_endif
> tlbi alle2
> dsb sy
>
> - /*
> - * Preserve all the RES1 bits while setting the default flags,
> - * as well as the EE bit on BE. Drop the A flag since the compiler
> - * is allowed to generate unaligned accesses.
> - */
> - mov_q x0, (SCTLR_EL2_RES1 | (SCTLR_ELx_FLAGS & ~SCTLR_ELx_A))
> -CPU_BE( orr x0, x0, #SCTLR_ELx_EE)
> + mov_q x0, INIT_SCTLR_EL2_MMU_ON
> alternative_if ARM64_HAS_ADDRESS_AUTH
> mov_q x1, (SCTLR_ELx_ENIA | SCTLR_ELx_ENIB | \
> SCTLR_ELx_ENDA | SCTLR_ELx_ENDB)
Beautiful!
With that, you can have my ack on the whole series:
Acked-by: Will Deacon <will@kernel.org>
Will
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next prev parent reply other threads:[~2021-03-10 18:21 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-10 15:26 [PATCH 0/4] KVM: arm64: Running the EL2 nVHE code with WXN Marc Zyngier
2021-03-10 15:26 ` [PATCH 1/4] arm64: Use INIT_SCTLR_EL1_MMU_OFF to disable the MMU on CPU restart Marc Zyngier
2021-03-10 15:26 ` [PATCH 2/4] KVM: arm64: Use INIT_SCTLR_EL2_MMU_OFF to disable the MMU on KVM teardown Marc Zyngier
2021-03-10 15:26 ` [PATCH 3/4] KVM: arm64: Rename SCTLR_ELx_FLAGS to SCTLR_EL2_FLAGS Marc Zyngier
2021-03-10 15:46 ` Will Deacon
2021-03-10 16:05 ` Marc Zyngier
2021-03-10 16:15 ` Will Deacon
2021-03-10 17:49 ` Marc Zyngier
2021-03-10 18:20 ` Will Deacon [this message]
2021-03-11 11:35 ` Mark Rutland
2021-03-11 12:00 ` Mark Rutland
2021-03-10 15:26 ` [PATCH 4/4] KVM: arm64: Force SCTLR_EL2.WXN when running nVHE Marc Zyngier
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