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Tue, 12 Jul 2022 07:53:07 +0100 Date: Tue, 12 Jul 2022 07:52:51 +0100 Message-ID: <87fsj6lt4s.wl-maz@kernel.org> From: Marc Zyngier To: Reiji Watanabe Cc: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, Linux ARM , Schspa Shi , kernel-team@android.com, Oliver Upton Subject: Re: [PATCH 08/19] KVM: arm64: vgic-v3: Push user access into vgic_v3_cpu_sysregs_uaccess() In-Reply-To: References: <20220706164304.1582687-1-maz@kernel.org> <20220706164304.1582687-9-maz@kernel.org> 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/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.104.136.29 X-SA-Exim-Rcpt-To: reijiw@google.com, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, schspa@gmail.com, kernel-team@android.com, oliver.upton@linux.dev 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-20220711_235310_530602_5F5F8616 X-CRM114-Status: GOOD ( 32.67 ) 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 Hi Reiji, On Tue, 12 Jul 2022 07:11:39 +0100, Reiji Watanabe wrote: > > Hi Marc, > > On Wed, Jul 6, 2022 at 9:43 AM Marc Zyngier wrote: > > > > In order to start making the vgic sysreg access from userspace > > similar to all the other sysregs, push the userspace memory > > access one level down into vgic_v3_cpu_sysregs_uaccess(). > > > > The next step will be to rely on the sysreg infrastructure > > to perform this task. > > > > Signed-off-by: Marc Zyngier > > --- > > arch/arm64/kvm/vgic-sys-reg-v3.c | 22 +++++++++++++------ > > arch/arm64/kvm/vgic/vgic-kvm-device.c | 31 ++++++--------------------- > > arch/arm64/kvm/vgic/vgic.h | 4 ++-- > > 3 files changed, 23 insertions(+), 34 deletions(-) > > > > diff --git a/arch/arm64/kvm/vgic-sys-reg-v3.c b/arch/arm64/kvm/vgic-sys-reg-v3.c > > index 85a5e1d15e9f..8c56e285fde9 100644 > > --- a/arch/arm64/kvm/vgic-sys-reg-v3.c > > +++ b/arch/arm64/kvm/vgic-sys-reg-v3.c > > @@ -278,15 +278,21 @@ int vgic_v3_has_cpu_sysregs_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr * > > return -ENXIO; > > } > > > > -int vgic_v3_cpu_sysregs_uaccess(struct kvm_vcpu *vcpu, bool is_write, u64 id, > > - u64 *reg) > > +int vgic_v3_cpu_sysregs_uaccess(struct kvm_vcpu *vcpu, > > + struct kvm_device_attr *attr, > > + bool is_write) > > { > > + u64 __user *uaddr = (u64 __user *)(long)attr->addr; > > struct sys_reg_params params; > > const struct sys_reg_desc *r; > > - u64 sysreg = (id & KVM_DEV_ARM_VGIC_SYSREG_MASK) | KVM_REG_SIZE_U64; > > + u64 sysreg; > > > > - if (is_write) > > - params.regval = *reg; > > + sysreg = (attr->attr & KVM_DEV_ARM_VGIC_SYSREG_MASK) | KVM_REG_SIZE_U64; > > Why don't you use attr_to_id() here ? This actually happens in the following patch. Happy to move the change here though. > > > > + > > + if (is_write) { > > + if (get_user(params.regval, uaddr)) > > + return -EFAULT; > > + } > > params.is_write = is_write; > > > > r = find_reg_by_id(sysreg, ¶ms, gic_v3_icc_reg_descs, > > @@ -297,8 +303,10 @@ int vgic_v3_cpu_sysregs_uaccess(struct kvm_vcpu *vcpu, bool is_write, u64 id, > > if (!r->access(vcpu, ¶ms, r)) > > return -EINVAL; > > > > - if (!is_write) > > - *reg = params.regval; > > + if (!is_write) { > > + if (put_user(params.regval, uaddr)) > > + return -EFAULT; > > + } > > > > return 0; > > } > > diff --git a/arch/arm64/kvm/vgic/vgic-kvm-device.c b/arch/arm64/kvm/vgic/vgic-kvm-device.c > > index c6d52a1fd9c8..d8269300632d 100644 > > --- a/arch/arm64/kvm/vgic/vgic-kvm-device.c > > +++ b/arch/arm64/kvm/vgic/vgic-kvm-device.c > > @@ -561,14 +561,9 @@ static int vgic_v3_attr_regs_access(struct kvm_device *dev, > > if (!is_write) > > *reg = tmp32; > > break; > > - case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS: { > > - u64 regid; > > - > > - regid = (attr->attr & KVM_DEV_ARM_VGIC_SYSREG_INSTR_MASK); > > - ret = vgic_v3_cpu_sysregs_uaccess(vcpu, is_write, > > - regid, reg); > > + case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS: > > + ret = vgic_v3_cpu_sysregs_uaccess(vcpu, attr, is_write); > > Nit: Since @reg that is passed to vgic_v3_attr_regs_access() will be NULL > for KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS, I think it would be more clear > if you could update the comment for vgic_v3_attr_regs_access accordingly. > > ---- > /* > * vgic_v3_attr_regs_access - allows user space to access VGIC v3 state > * > * @dev: kvm device handle > * @attr: kvm device attribute > * @reg: address the value is read or written > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > * @is_write: true if userspace is writing a register > */ > static int vgic_v3_attr_regs_access(struct kvm_device *dev, > struct kvm_device_attr *attr, > u64 *reg, bool is_write) @reg disappears completely in patch #12. Do you see value in rewriting this comment even if I end-up removing it 4 patches down the line? Thanks, 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