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From:   isaku.yamahata@intel.com
To:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     isaku.yamahata@intel.com, isaku.yamahata@gmail.com,
        Paolo Bonzini <pbonzini@redhat.com>, erdemaktas@google.com,
        Sean Christopherson <seanjc@google.com>,
        Sagi Shahar <sagis@google.com>
Subject: [RFC PATCH v6 024/104] KVM: TDX: Add place holder for TDX VM specific mem_enc_op ioctl
Date:   Thu,  5 May 2022 11:14:18 -0700
Message-Id: <46c9ee65c92b526f8c1c009099a08a2e0b291649.1651774250.git.isaku.yamahata@intel.com>
In-Reply-To: <cover.1651774250.git.isaku.yamahata@intel.com>
References: <cover.1651774250.git.isaku.yamahata@intel.com>
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From: Isaku Yamahata <isaku.yamahata@intel.com>

Add a place holder function for TDX specific VM-scoped ioctl as mem_enc_op.
TDX specific sub-commands will be added to retrieve/pass TDX specific
parameters.

KVM_MEMORY_ENCRYPT_OP was introduced for VM-scoped operations specific for
guest state-protected VM.  It defined subcommands for technology-specific
operations under KVM_MEMORY_ENCRYPT_OP.  Despite its name, the subcommands
are not limited to memory encryption, but various technology-specific
operations are defined.  It's natural to repurpose KVM_MEMORY_ENCRYPT_OP
for TDX specific operations and define subcommands.

TDX requires VM-scoped, and VCPU-scoped TDX-specific operations for device
model, for example, qemu.  Getting system-wide parameters, TDX-specific VM
initialization, and TDX-specific vCPU initialization.  Which requires KVM
vCPU-scoped operations in addition to the existing VM-scoped operations.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
 arch/x86/kvm/vmx/main.c    |  9 +++++++++
 arch/x86/kvm/vmx/tdx.c     | 26 ++++++++++++++++++++++++++
 arch/x86/kvm/vmx/x86_ops.h |  4 ++++
 3 files changed, 39 insertions(+)

diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index 7b497ed1f21c..067f5de56c53 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -73,6 +73,14 @@ static void vt_vm_free(struct kvm *kvm)
 		return tdx_vm_free(kvm);
 }
 
+static int vt_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
+{
+	if (!is_td(kvm))
+		return -ENOTTY;
+
+	return tdx_vm_ioctl(kvm, argp);
+}
+
 struct kvm_x86_ops vt_x86_ops __initdata = {
 	.name = "kvm_intel",
 
@@ -214,6 +222,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
 	.vcpu_deliver_sipi_vector = kvm_vcpu_deliver_sipi_vector,
 
 	.dev_mem_enc_ioctl = tdx_dev_ioctl,
+	.mem_enc_ioctl = vt_mem_enc_ioctl,
 };
 
 struct kvm_x86_init_ops vt_init_ops __initdata = {
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 07b69ffbe55b..a4be3ef313b2 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -438,6 +438,32 @@ int tdx_dev_ioctl(void __user *argp)
 	return 0;
 }
 
+int tdx_vm_ioctl(struct kvm *kvm, void __user *argp)
+{
+	struct kvm_tdx_cmd tdx_cmd;
+	int r;
+
+	if (copy_from_user(&tdx_cmd, argp, sizeof(struct kvm_tdx_cmd)))
+		return -EFAULT;
+	if (tdx_cmd.error || tdx_cmd.unused)
+		return -EINVAL;
+
+	mutex_lock(&kvm->lock);
+
+	switch (tdx_cmd.id) {
+	default:
+		r = -EINVAL;
+		goto out;
+	}
+
+	if (copy_to_user(argp, &tdx_cmd, sizeof(struct kvm_tdx_cmd)))
+		r = -EFAULT;
+
+out:
+	mutex_unlock(&kvm->lock);
+	return r;
+}
+
 int __init tdx_module_setup(void)
 {
 	const struct tdsysinfo_struct *tdsysinfo;
diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
index 75e6cdcb06f5..1ff555cc6c17 100644
--- a/arch/x86/kvm/vmx/x86_ops.h
+++ b/arch/x86/kvm/vmx/x86_ops.h
@@ -137,6 +137,8 @@ int tdx_dev_ioctl(void __user *argp);
 int tdx_vm_init(struct kvm *kvm);
 void tdx_mmu_release_hkid(struct kvm *kvm);
 void tdx_vm_free(struct kvm *kvm);
+
+int tdx_vm_ioctl(struct kvm *kvm, void __user *argp);
 #else
 static inline int tdx_hardware_setup(struct kvm_x86_ops *x86_ops) { return 0; }
 static inline bool tdx_is_vm_type_supported(unsigned long type) { return false; }
@@ -147,6 +149,8 @@ static inline int tdx_vm_init(struct kvm *kvm) { return -EOPNOTSUPP; }
 static inline void tdx_mmu_release_hkid(struct kvm *kvm) {}
 static inline void tdx_flush_shadow_all_private(struct kvm *kvm) {}
 static inline void tdx_vm_free(struct kvm *kvm) {}
+
+static inline int tdx_vm_ioctl(struct kvm *kvm, void __user *argp) { return -EOPNOTSUPP; }
 #endif
 
 #endif /* __KVM_X86_VMX_X86_OPS_H */
-- 
2.25.1