From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Martin Subject: Re: [PATCH v2 12/12] KVM: arm64: BTI: Reset BTYPE when skipping emulated instructions Date: Fri, 11 Oct 2019 15:44:51 +0100 Message-ID: <20191011144451.GI27757@arm.com> References: <1570733080-21015-1-git-send-email-Dave.Martin@arm.com> <1570733080-21015-13-git-send-email-Dave.Martin@arm.com> <20191011142454.GD33537@lakrids.cambridge.arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20191011142454.GD33537@lakrids.cambridge.arm.com> Sender: linux-kernel-owner@vger.kernel.org To: Mark Rutland Cc: Paul Elliott , Peter Zijlstra , Catalin Marinas , Will Deacon , Yu-cheng Yu , Amit Kachhap , Vincenzo Frascino , linux-arch@vger.kernel.org, Eugene Syromiatnikov , Szabolcs Nagy , "H.J. Lu" , Andrew Jones , Kees Cook , Arnd Bergmann , Jann Horn , Richard Henderson , Kristina =?utf-8?Q?Mart=C5=A1enko?= , Mark Brown , Thomas Gleixner , linux-arm-kernel@lists.infradead.or List-Id: linux-arch.vger.kernel.org On Fri, Oct 11, 2019 at 03:24:55PM +0100, Mark Rutland wrote: > On Thu, Oct 10, 2019 at 07:44:40PM +0100, Dave Martin wrote: > > Since normal execution of any non-branch instruction resets the > > PSTATE BTYPE field to 0, so do the same thing when emulating a > > trapped instruction. > > > > Branches don't trap directly, so we should never need to assign a > > non-zero value to BTYPE here. > > > > Signed-off-by: Dave Martin > > --- > > arch/arm64/include/asm/kvm_emulate.h | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h > > index d69c1ef..33957a12 100644 > > --- a/arch/arm64/include/asm/kvm_emulate.h > > +++ b/arch/arm64/include/asm/kvm_emulate.h > > @@ -452,8 +452,10 @@ static inline void kvm_skip_instr(struct kvm_vcpu *vcpu, bool is_wide_instr) > > { > > if (vcpu_mode_is_32bit(vcpu)) > > kvm_skip_instr32(vcpu, is_wide_instr); > > - else > > + else { > > *vcpu_pc(vcpu) += 4; > > + *vcpu_cpsr(vcpu) &= ~(u64)PSR_BTYPE_MASK; > > + } > > Style nit: both sides of an if-else should match brace-wise. i.e. please > add braces to the other side. Will fix. Strange, checkpatch didn't catch that, maybe because only one arm of the if was patched. > As with the prior patch, the u64 cast can also go. > > Otherwise, this looks right to me. For some reason I thought there was a different prevailing style in the KVM code, but now I see no evidence of that. Will fix. Thanks for the review. Cheers ---Dave From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com ([217.140.110.172]:34594 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726671AbfJKOo5 (ORCPT ); Fri, 11 Oct 2019 10:44:57 -0400 Date: Fri, 11 Oct 2019 15:44:51 +0100 From: Dave Martin Subject: Re: [PATCH v2 12/12] KVM: arm64: BTI: Reset BTYPE when skipping emulated instructions Message-ID: <20191011144451.GI27757@arm.com> References: <1570733080-21015-1-git-send-email-Dave.Martin@arm.com> <1570733080-21015-13-git-send-email-Dave.Martin@arm.com> <20191011142454.GD33537@lakrids.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191011142454.GD33537@lakrids.cambridge.arm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Mark Rutland Cc: Paul Elliott , Peter Zijlstra , Catalin Marinas , Will Deacon , Yu-cheng Yu , Amit Kachhap , Vincenzo Frascino , linux-arch@vger.kernel.org, Eugene Syromiatnikov , Szabolcs Nagy , "H.J. Lu" , Andrew Jones , Kees Cook , Arnd Bergmann , Jann Horn , Richard Henderson , Kristina =?utf-8?Q?Mart=C5=A1enko?= , Mark Brown , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Florian Weimer , linux-kernel@vger.kernel.org, Sudakshina Das Message-ID: <20191011144451.suNKz48sTRwf5XPQPQBOB-Kwg5ykixdnsRnO5kxjrUE@z> On Fri, Oct 11, 2019 at 03:24:55PM +0100, Mark Rutland wrote: > On Thu, Oct 10, 2019 at 07:44:40PM +0100, Dave Martin wrote: > > Since normal execution of any non-branch instruction resets the > > PSTATE BTYPE field to 0, so do the same thing when emulating a > > trapped instruction. > > > > Branches don't trap directly, so we should never need to assign a > > non-zero value to BTYPE here. > > > > Signed-off-by: Dave Martin > > --- > > arch/arm64/include/asm/kvm_emulate.h | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h > > index d69c1ef..33957a12 100644 > > --- a/arch/arm64/include/asm/kvm_emulate.h > > +++ b/arch/arm64/include/asm/kvm_emulate.h > > @@ -452,8 +452,10 @@ static inline void kvm_skip_instr(struct kvm_vcpu *vcpu, bool is_wide_instr) > > { > > if (vcpu_mode_is_32bit(vcpu)) > > kvm_skip_instr32(vcpu, is_wide_instr); > > - else > > + else { > > *vcpu_pc(vcpu) += 4; > > + *vcpu_cpsr(vcpu) &= ~(u64)PSR_BTYPE_MASK; > > + } > > Style nit: both sides of an if-else should match brace-wise. i.e. please > add braces to the other side. Will fix. Strange, checkpatch didn't catch that, maybe because only one arm of the if was patched. > As with the prior patch, the u64 cast can also go. > > Otherwise, this looks right to me. For some reason I thought there was a different prevailing style in the KVM code, but now I see no evidence of that. Will fix. Thanks for the review. Cheers ---Dave