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[34.68.225.194]) by smtp.gmail.com with ESMTPSA id f1-20020a056e020b4100b002c68e176293sm247658ilu.87.2022.03.15.16.13.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Mar 2022 16:13:12 -0700 (PDT) Date: Tue, 15 Mar 2022 23:13:09 +0000 From: Oliver Upton To: Marc Zyngier Subject: Re: [PATCH 4/4] KVM: arm64: vgic-v3: Advertise GICR_CTLR.{IR, CES} as a new GICD_IIDR revision Message-ID: References: <20220314164044.772709-1-maz@kernel.org> <20220314164044.772709-5-maz@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220314164044.772709-5-maz@kernel.org> Cc: Andre Przywara , kernel-team@android.com, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Hi Marc, On Mon, Mar 14, 2022 at 04:40:44PM +0000, Marc Zyngier wrote: > Since adversising GICR_CTLR.{IC,CES} is directly observable from > a guest, we need to make it selectable from userspace. > > For that, bump the default GICD_IIDR revision and let userspace > downgrade it to the previous default. For GICv2, the two distributor > revisions are strictly equivalent. > > Signed-off-by: Marc Zyngier > --- > arch/arm64/kvm/vgic/vgic-init.c | 7 ++++++- > arch/arm64/kvm/vgic/vgic-mmio-v2.c | 18 +++++++++++++++--- > arch/arm64/kvm/vgic/vgic-mmio-v3.c | 23 +++++++++++++++++++++-- > include/kvm/arm_vgic.h | 3 +++ > 4 files changed, 45 insertions(+), 6 deletions(-) > > diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c > index fc00304fe7d8..f84e04f334c6 100644 > --- a/arch/arm64/kvm/vgic/vgic-init.c > +++ b/arch/arm64/kvm/vgic/vgic-init.c > @@ -319,7 +319,12 @@ int vgic_init(struct kvm *kvm) > > vgic_debug_init(kvm); > > - dist->implementation_rev = 2; > + /* > + * If userspace didn't set the GIC implementation revision, > + * default to the latest and greatest. You know want it. > + */ > + if (!dist->implementation_rev) > + dist->implementation_rev = KVM_VGIC_IMP_REV_LATEST; > dist->initialized = true; > > out: > diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v2.c b/arch/arm64/kvm/vgic/vgic-mmio-v2.c > index 12e4c223e6b8..f2246c4ca812 100644 > --- a/arch/arm64/kvm/vgic/vgic-mmio-v2.c > +++ b/arch/arm64/kvm/vgic/vgic-mmio-v2.c > @@ -73,9 +73,13 @@ static int vgic_mmio_uaccess_write_v2_misc(struct kvm_vcpu *vcpu, > gpa_t addr, unsigned int len, > unsigned long val) > { > + struct vgic_dist *dist = &vcpu->kvm->arch.vgic; > + u32 reg; > + > switch (addr & 0x0c) { > case GIC_DIST_IIDR: > - if (val != vgic_mmio_read_v2_misc(vcpu, addr, len)) > + reg = vgic_mmio_read_v2_misc(vcpu, addr, len); > + if ((reg ^ val) & ~GICD_IIDR_REVISION_MASK) > return -EINVAL; > > /* > @@ -87,8 +91,16 @@ static int vgic_mmio_uaccess_write_v2_misc(struct kvm_vcpu *vcpu, > * migration from old kernels to new kernels with legacy > * userspace. > */ > - vcpu->kvm->arch.vgic.v2_groups_user_writable = true; > - return 0; > + reg = FIELD_GET(GICD_IIDR_REVISION_MASK, reg); > + switch (reg) { > + case KVM_VGIC_IMP_REV_2: > + case KVM_VGIC_IMP_REV_3: > + dist->v2_groups_user_writable = true; Could you eliminate this bool and just pivot off of the implementation version? > + dist->implementation_rev = reg; > + return 0; > + default: > + return -EINVAL; > + } > } > > vgic_mmio_write_v2_misc(vcpu, addr, len, val); > diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c > index a6be403996c6..4c8e4f83e3d1 100644 > --- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c > +++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c > @@ -155,13 +155,27 @@ static int vgic_mmio_uaccess_write_v3_misc(struct kvm_vcpu *vcpu, > unsigned long val) > { > struct vgic_dist *dist = &vcpu->kvm->arch.vgic; > + u32 reg; > > switch (addr & 0x0c) { > case GICD_TYPER2: > - case GICD_IIDR: > if (val != vgic_mmio_read_v3_misc(vcpu, addr, len)) > return -EINVAL; > return 0; > + case GICD_IIDR: > + reg = vgic_mmio_read_v3_misc(vcpu, addr, len); > + if ((reg ^ val) & ~GICD_IIDR_REVISION_MASK) > + return -EINVAL; > + > + reg = FIELD_GET(GICD_IIDR_REVISION_MASK, reg); > + switch (reg) { > + case KVM_VGIC_IMP_REV_2: > + case KVM_VGIC_IMP_REV_3: > + dist->implementation_rev = reg; > + return 0; > + default: > + return -EINVAL; > + } > case GICD_CTLR: > /* Not a GICv4.1? No HW SGIs */ > if (!kvm_vgic_global_state.has_gicv4_1) > @@ -232,8 +246,13 @@ static unsigned long vgic_mmio_read_v3r_ctlr(struct kvm_vcpu *vcpu, > gpa_t addr, unsigned int len) > { > struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu; > + unsigned long val; > + > + val = atomic_read(&vgic_cpu->ctlr); > + if (vcpu->kvm->arch.vgic.implementation_rev >= KVM_VGIC_IMP_REV_3) That's a lot of indirection :) Could you make a helper for getting at the implementation revision from a vCPU pointer? > + val |= GICR_CTLR_IR | GICR_CTLR_CES; > > - return vgic_cpu->lpis_enabled ? GICR_CTLR_ENABLE_LPIS : 0; > + return val; > } > > static void vgic_mmio_write_v3r_ctlr(struct kvm_vcpu *vcpu, > diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h > index 401236f97cf2..2d8f2e90edc2 100644 > --- a/include/kvm/arm_vgic.h > +++ b/include/kvm/arm_vgic.h > @@ -231,6 +231,9 @@ struct vgic_dist { > > /* Implementation revision as reported in the GICD_IIDR */ > u32 implementation_rev; > +#define KVM_VGIC_IMP_REV_2 2 /* GICv2 restorable groups */ > +#define KVM_VGIC_IMP_REV_3 3 /* GICv3 GICR_CTLR.{IW,CES,RWP} */ > +#define KVM_VGIC_IMP_REV_LATEST KVM_VGIC_IMP_REV_3 > > /* Userspace can write to GICv2 IGROUPR */ > bool v2_groups_user_writable; > -- > 2.34.1 > > _______________________________________________ > kvmarm mailing list > kvmarm@lists.cs.columbia.edu > https://lists.cs.columbia.edu/mailman/listinfo/kvmarm _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm