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Wed, 27 May 2020 11:04:08 +0100 MIME-Version: 1.0 Date: Wed, 27 May 2020 11:04:08 +0100 From: Marc Zyngier To: James Morse Subject: Re: [PATCH 10/26] KVM: arm64: Refactor vcpu_{read,write}_sys_reg In-Reply-To: <09da829c-1640-40fe-313f-df021759fb34@arm.com> References: <20200422120050.3693593-1-maz@kernel.org> <20200422120050.3693593-11-maz@kernel.org> <09da829c-1640-40fe-313f-df021759fb34@arm.com> User-Agent: Roundcube Webmail/1.4.4 Message-ID: <1612302e289ba15fb0ffbfba5ea18e3b@kernel.org> X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: james.morse@arm.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, andre.przywara@arm.com, christoffer.dall@arm.com, Dave.Martin@arm.com, jintack@cs.columbia.edu, alexandru.elisei@arm.com, gcherian@marvell.com, prime.zeng@hisilicon.com, will@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200527_030411_023191_6DEF445B X-CRM114-Status: GOOD ( 14.46 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , kvm@vger.kernel.org, Suzuki K Poulose , Jintack Lim , Andre Przywara , Christoffer Dall , kvmarm@lists.cs.columbia.edu, Will Deacon , George Cherian , Julien Thierry , "Zengtao \(B\)" , Catalin Marinas , Alexandru Elisei , Dave Martin , linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2020-05-26 17:28, James Morse wrote: > Hi Marc, > > On 22/04/2020 13:00, Marc Zyngier wrote: >> Extract the direct HW accessors for later reuse. > >> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c >> index 51db934702b64..46f218982df8c 100644 >> --- a/arch/arm64/kvm/sys_regs.c >> +++ b/arch/arm64/kvm/sys_regs.c > >> +u64 vcpu_read_sys_reg(const struct kvm_vcpu *vcpu, int reg) >> +{ >> + u64 val = 0x8badf00d8badf00d; >> + >> + if (!vcpu->arch.sysregs_loaded_on_cpu) { >> + goto memory_read; >> } >> >> -immediate_write: >> + if (__vcpu_read_sys_reg_from_cpu(reg, &val)) >> + return val; >> + >> +memory_read: >> + return __vcpu_sys_reg(vcpu, reg); >> +} > > > The goto here is a bit odd, is it just an artefact of how we got here? That's because a lot of this changes when NV gets added to the mix, see [1]. > Is this easier on the eye?: > | u64 vcpu_read_sys_reg(const struct kvm_vcpu *vcpu, int reg) > | { > | u64 val = 0x8badf00d8badf00d; > | > | if (vcpu->arch.sysregs_loaded_on_cpu && > | __vcpu_read_sys_reg_from_cpu(reg, &val)) > | return val; > | > | return __vcpu_sys_reg(vcpu, reg); > | } Definitely. I don't mind reworking the NV branch so that the label gets introduced there. >> +void vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, int reg) >> +{ >> + if (!vcpu->arch.sysregs_loaded_on_cpu) >> + goto memory_write; >> + >> + if (__vcpu_write_sys_reg_to_cpu(val, reg)) >> + return; >> + >> +memory_write: >> __vcpu_sys_reg(vcpu, reg) = val; >> } > > Again I think its clearer without the goto.... > > > Regardless: > Reviewed-by: James Morse Thanks, M. [1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/commit/?h=kvm-arm64/nv-5.7-rc1-WIP&id=11f3217d39a602cbfac7d08064c8b31afb57348e -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel