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Mon, 27 Nov 2023 23:44:03 -0800 (PST) X-Google-Smtp-Source: AGHT+IFSrzOfVFXXaYd5bwOlRnKvmus8guyrTlPsH/3Zw/WlyXTEMG/LN54CkOejsPqYFMufXdBSmw== X-Received: by 2002:adf:f88d:0:b0:332:e9ff:7fad with SMTP id u13-20020adff88d000000b00332e9ff7fadmr10210233wrp.12.1701157443271; Mon, 27 Nov 2023 23:44:03 -0800 (PST) Received: from starship ([77.137.131.4]) by smtp.gmail.com with ESMTPSA id r5-20020a5d6c65000000b00332f6202b82sm8573153wrz.9.2023.11.27.23.44.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Nov 2023 23:44:02 -0800 (PST) Message-ID: <4f3d9563a4246a97eae28486eee1730d134b222b.camel@redhat.com> Subject: Re: [RFC 26/33] KVM: x86: hyper-vsm: Allow setting per-VTL memory attributes From: Maxim Levitsky To: Nicolas Saenz Julienne , kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, pbonzini@redhat.com, seanjc@google.com, vkuznets@redhat.com, anelkz@amazon.com, graf@amazon.com, dwmw@amazon.co.uk, jgowans@amazon.com, corbert@lwn.net, kys@microsoft.com, haiyangz@microsoft.com, decui@microsoft.com, x86@kernel.org, linux-doc@vger.kernel.org Date: Tue, 28 Nov 2023 09:44:00 +0200 In-Reply-To: <20231108111806.92604-27-nsaenz@amazon.com> References: <20231108111806.92604-1-nsaenz@amazon.com> <20231108111806.92604-27-nsaenz@amazon.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2023-11-08 at 11:17 +0000, Nicolas Saenz Julienne wrote: > Introduce KVM_SET_MEMORY_ATTRIBUTES ioctl support for VTL KVM devices. > The attributes are stored in an xarray private to the VTL device. > > The following memory attributes are supported: > - KVM_MEMORY_ATTRIBUTE_READ > - KVM_MEMORY_ATTRIBUTE_WRITE > - KVM_MEMORY_ATTRIBUTE_EXECUTE > - KVM_MEMORY_ATTRIBUTE_NO_ACCESS > Although only some combinations are valid, see code comment below. > > Signed-off-by: Nicolas Saenz Julienne > --- > arch/x86/kvm/hyperv.c | 61 +++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 61 insertions(+) > > diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c > index 0d8402dba596..bcace0258af1 100644 > --- a/arch/x86/kvm/hyperv.c > +++ b/arch/x86/kvm/hyperv.c > @@ -62,6 +62,10 @@ > */ > #define HV_EXT_CALL_MAX (HV_EXT_CALL_QUERY_CAPABILITIES + 64) > > +#define KVM_HV_VTL_ATTRS \ > + (KVM_MEMORY_ATTRIBUTE_READ | KVM_MEMORY_ATTRIBUTE_WRITE | \ > + KVM_MEMORY_ATTRIBUTE_EXECUTE | KVM_MEMORY_ATTRIBUTE_NO_ACCESS) > + > static void stimer_mark_pending(struct kvm_vcpu_hv_stimer *stimer, > bool vcpu_kick); > > @@ -3025,6 +3029,7 @@ int kvm_vm_ioctl_get_hv_vsm_state(struct kvm *kvm, struct kvm_hv_vsm_state *stat > > struct kvm_hv_vtl_dev { > int vtl; > + struct xarray mem_attrs; > }; > > static int kvm_hv_vtl_get_attr(struct kvm_device *dev, > @@ -3047,16 +3052,71 @@ static void kvm_hv_vtl_release(struct kvm_device *dev) > { > struct kvm_hv_vtl_dev *vtl_dev = dev->private; > > + xa_destroy(&vtl_dev->mem_attrs); > kfree(vtl_dev); > kfree(dev); /* alloc by kvm_ioctl_create_device, free by .release */ > } > > +/* > + * The TLFS lists the valid memory protection combinations (15.9.3): > + * - No access > + * - Read-only, no execute > + * - Read-only, execute > + * - Read/write, no execute > + * - Read/write, execute > + */ > +static bool kvm_hv_validate_vtl_mem_attributes(struct kvm_memory_attributes *attrs) > +{ > + u64 attr = attrs->attributes; > + > + if (attr & ~KVM_HV_VTL_ATTRS) > + return false; > + > + if (attr == KVM_MEMORY_ATTRIBUTE_NO_ACCESS) > + return true; > + > + if (!(attr & KVM_MEMORY_ATTRIBUTE_READ)) > + return false; > + > + return true; > +} > + > +static long kvm_hv_vtl_ioctl(struct kvm_device *dev, unsigned int ioctl, > + unsigned long arg) > +{ > + switch (ioctl) { > + case KVM_SET_MEMORY_ATTRIBUTES: { > + struct kvm_hv_vtl_dev *vtl_dev = dev->private; > + struct kvm_memory_attributes attrs; > + int r; > + > + if (copy_from_user(&attrs, (void __user *)arg, sizeof(attrs))) > + return -EFAULT; > + > + r = -EINVAL; > + if (!kvm_hv_validate_vtl_mem_attributes(&attrs)) > + return r; > + > + r = kvm_ioctl_set_mem_attributes(dev->kvm, &vtl_dev->mem_attrs, > + KVM_HV_VTL_ATTRS, &attrs); > + if (r) > + return r; > + break; > + } > + default: > + return -ENOTTY; > + } > + > + return 0; > +} > + > static int kvm_hv_vtl_create(struct kvm_device *dev, u32 type); > > static struct kvm_device_ops kvm_hv_vtl_ops = { > .name = "kvm-hv-vtl", > .create = kvm_hv_vtl_create, > .release = kvm_hv_vtl_release, > + .ioctl = kvm_hv_vtl_ioctl, > .get_attr = kvm_hv_vtl_get_attr, > }; > > @@ -3076,6 +3136,7 @@ static int kvm_hv_vtl_create(struct kvm_device *dev, u32 type) > vtl++; > > vtl_dev->vtl = vtl; > + xa_init(&vtl_dev->mem_attrs); > dev->private = vtl_dev; > > return 0; It makes sense, but hopefully we won't need it if we adopt the VM per VTL approach. Best regards, Maxim Levitsky