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Wed, 17 May 2023 08:41:15 +0100 Date: Wed, 17 May 2023 08:41:14 +0100 Message-ID: <86wn17l811.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 v8 2/6] KVM: arm64: Save ID registers' sanitized value per guest In-Reply-To: <20230503171618.2020461-3-jingzhangos@google.com> References: <20230503171618.2020461-1-jingzhangos@google.com> <20230503171618.2020461-3-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-20230517_004118_882746_02B06907 X-CRM114-Status: GOOD ( 36.81 ) 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 Wed, 03 May 2023 18:16:14 +0100, Jing Zhang wrote: > > Introduce id_regs[] in kvm_arch as a storage of guest's ID registers, > and save ID registers' sanitized value in the array at KVM_CREATE_VM. > Use the saved ones when ID registers are read by the guest or > userspace (via KVM_GET_ONE_REG). > > No functional change intended. > > Co-developed-by: Reiji Watanabe > Signed-off-by: Reiji Watanabe > Signed-off-by: Jing Zhang > --- > arch/arm64/include/asm/kvm_host.h | 20 ++++++++++++++ > arch/arm64/kvm/arm.c | 1 + > arch/arm64/kvm/id_regs.c | 46 +++++++++++++++++++++++++------ > arch/arm64/kvm/sys_regs.c | 11 +++++++- > arch/arm64/kvm/sys_regs.h | 3 +- > 5 files changed, 69 insertions(+), 12 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index bcd774d74f34..a7d4d9e093e3 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -177,6 +177,21 @@ struct kvm_smccc_features { > unsigned long vendor_hyp_bmap; > }; > > +/* > + * Emulated CPU ID registers per VM > + * (Op0, Op1, CRn, CRm, Op2) of the ID registers to be saved in it > + * is (3, 0, 0, crm, op2), where 1<=crm<8, 0<=op2<8. > + * > + * These emulated idregs are VM-wide, but accessed from the context of a vCPU. > + * Access to id regs are guarded by kvm_arch.config_lock. > + */ > +#define KVM_ARM_ID_REG_NUM 56 You already have this as part of patch #1 in another include file, and then move it here. Surely you can do that in one go. I'd also like it to be defined in terms of encodings, and not as a raw value. > +#define IDREG_IDX(id) (((sys_reg_CRm(id) - 1) << 3) | sys_reg_Op2(id)) > +#define IDREG(kvm, id) kvm->arch.idregs.regs[IDREG_IDX(id)] Missing brackets around 'kvm'. > +struct kvm_idregs { > + u64 regs[KVM_ARM_ID_REG_NUM]; > +}; > + > typedef unsigned int pkvm_handle_t; > > struct kvm_protected_vm { > @@ -243,6 +258,9 @@ struct kvm_arch { > /* Hypercall features firmware registers' descriptor */ > struct kvm_smccc_features smccc_feat; > > + /* Emulated CPU ID registers */ > + struct kvm_idregs idregs; > + > /* > * For an untrusted host VM, 'pkvm.handle' is used to lookup > * the associated pKVM instance in the hypervisor. > @@ -1008,6 +1026,8 @@ int kvm_arm_vcpu_arch_has_attr(struct kvm_vcpu *vcpu, > long kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm, > struct kvm_arm_copy_mte_tags *copy_tags); > > +void kvm_arm_init_id_regs(struct kvm *kvm); > + > /* Guest/host FPSIMD coordination helpers */ > int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu); > void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu); > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > index 4b2e16e696a8..e34744c36406 100644 > --- a/arch/arm64/kvm/arm.c > +++ b/arch/arm64/kvm/arm.c > @@ -153,6 +153,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) > > set_default_spectre(kvm); > kvm_arm_init_hypercalls(kvm); > + kvm_arm_init_id_regs(kvm); > > /* > * Initialise the default PMUver before there is a chance to > diff --git a/arch/arm64/kvm/id_regs.c b/arch/arm64/kvm/id_regs.c > index 96b4c43a5100..e769223bcee2 100644 > --- a/arch/arm64/kvm/id_regs.c > +++ b/arch/arm64/kvm/id_regs.c > @@ -52,16 +52,9 @@ static u8 pmuver_to_perfmon(u8 pmuver) > } > } > > -/* Read a sanitised cpufeature ID register by sys_reg_desc */ Why getting rid of this comment instead of moving it next to the (re-implemented) function? > -static u64 read_id_reg(const struct kvm_vcpu *vcpu, struct sys_reg_desc const *r) > +u64 kvm_arm_read_id_reg(const struct kvm_vcpu *vcpu, u32 id) > { > - u32 id = reg_to_encoding(r); > - u64 val; > - > - if (sysreg_visible_as_raz(vcpu, r)) > - return 0; > - > - val = read_sanitised_ftr_reg(id); > + u64 val = IDREG(vcpu->kvm, id); > > switch (id) { > case SYS_ID_AA64PFR0_EL1: > @@ -126,6 +119,14 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu, struct sys_reg_desc const *r > return val; > } > > +static u64 read_id_reg(const struct kvm_vcpu *vcpu, struct sys_reg_desc const *r) > +{ > + if (sysreg_visible_as_raz(vcpu, r)) > + return 0; > + > + return kvm_arm_read_id_reg(vcpu, reg_to_encoding(r)); > +} > + > /* cpufeature ID register access trap handlers */ > > static bool access_id_reg(struct kvm_vcpu *vcpu, > @@ -458,3 +459,30 @@ int emulate_id_reg(struct kvm_vcpu *vcpu, struct sys_reg_params *params) > > return 1; > } > + > +/* > + * Set the guest's ID registers that are defined in id_reg_descs[] > + * with ID_SANITISED() to the host's sanitized value. > + */ > +void kvm_arm_init_id_regs(struct kvm *kvm) > +{ > + u64 val; > + u32 id; > + int i; > + > + for (i = 0; i < ARRAY_SIZE(id_reg_descs); i++) { > + id = reg_to_encoding(&id_reg_descs[i]); > + > + /* > + * Some hidden ID registers which are not in arm64_ftr_regs[] > + * would cause warnings from read_sanitised_ftr_reg(). > + * Skip those ID registers to avoid the warnings. > + */ > + if (id_reg_descs[i].visibility == raz_visibility) > + /* Hidden or reserved ID register */ > + continue; Are you sure? What about other visibility attributes that are normally evaluated at runtime? This may work as a short term hack, but I'm not sure this is the correct long-term solution... 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