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Mon, 03 Apr 2023 13:27:25 +0100 Date: Mon, 03 Apr 2023 13:27:24 +0100 Message-ID: <86y1n9up5f.wl-maz@kernel.org> From: Marc Zyngier To: Jing Zhang Cc: KVM , KVMARM , ARMLinux , Oliver Upton , Will Deacon , Paolo Bonzini , James Morse , Alexandru Elisei , Suzuki K Poulose , Fuad Tabba , Reiji Watanabe , Raghavendra Rao Ananta Subject: Re: [PATCH v5 5/6] KVM: arm64: Introduce ID register specific descriptor In-Reply-To: <20230402183735.3011540-6-jingzhangos@google.com> References: <20230402183735.3011540-1-jingzhangos@google.com> <20230402183735.3011540-6-jingzhangos@google.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/28.2 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: jingzhangos@google.com, kvm@vger.kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, oupton@google.com, will@kernel.org, pbonzini@redhat.com, james.morse@arm.com, alexandru.elisei@arm.com, suzuki.poulose@arm.com, tabba@google.com, reijiw@google.com, rananta@google.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-20230403_052729_098898_D2657DA9 X-CRM114-Status: GOOD ( 24.97 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sun, 02 Apr 2023 19:37:34 +0100, Jing Zhang wrote: > > Introduce an ID feature register specific descriptor to include ID > register specific fields and callbacks besides its corresponding > general system register descriptor. > > No functional change intended. > > Co-developed-by: Reiji Watanabe > Signed-off-by: Reiji Watanabe > Signed-off-by: Jing Zhang > --- > arch/arm64/kvm/id_regs.c | 233 ++++++++++++++++++++++++++++---------- > arch/arm64/kvm/sys_regs.c | 2 +- > arch/arm64/kvm/sys_regs.h | 1 + > 3 files changed, 178 insertions(+), 58 deletions(-) > > diff --git a/arch/arm64/kvm/id_regs.c b/arch/arm64/kvm/id_regs.c > index e92eacb0ad32..af86001e2686 100644 > --- a/arch/arm64/kvm/id_regs.c > +++ b/arch/arm64/kvm/id_regs.c > @@ -18,6 +18,27 @@ > > #include "sys_regs.h" > > +struct id_reg_desc { > + const struct sys_reg_desc reg_desc; > + /* > + * ftr_bits points to the feature bits array defined in cpufeature.c for > + * writable CPU ID feature register. > + */ > + const struct arm64_ftr_bits *ftr_bits; Why do we need to keep this around? we already have all the required infrastructure to lookup a full arm64_ftr_reg. So why the added stuff? > + /* > + * Only bits with 1 are writable from userspace. > + * This mask might not be necessary in the future whenever all ID > + * registers are enabled as writable from userspace. > + */ > + const u64 writable_mask; > + /* > + * This function returns the KVM sanitised register value. > + * The value would be the same as the host kernel sanitised value if > + * there is no KVM sanitisation for this id register. > + */ > + u64 (*read_kvm_sanitised_reg)(const struct id_reg_desc *idr); Why can't this function return both the required value and a mask? Why can't it live in the sys_reg_desc structure? Frankly, I don't see a good reason to have this wrapper structure which makes things pointlessly complicated and prevent code sharing with the rest of the infrastructure. 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