From: Paolo Bonzini <pbonzini@redhat.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: michael.roth@amd.com, isaku.yamahata@intel.com
Subject: [PATCH v5 12/17] KVM: SEV: introduce KVM_SEV_INIT2 operation
Date: Thu, 4 Apr 2024 08:13:22 -0400 [thread overview]
Message-ID: <20240404121327.3107131-13-pbonzini@redhat.com> (raw)
In-Reply-To: <20240404121327.3107131-1-pbonzini@redhat.com>
The idea that no parameter would ever be necessary when enabling SEV or
SEV-ES for a VM was decidedly optimistic. In fact, in some sense it's
already a parameter whether SEV or SEV-ES is desired. Another possible
source of variability is the desired set of VMSA features, as that affects
the measurement of the VM's initial state and cannot be changed
arbitrarily by the hypervisor.
Create a new sub-operation for KVM_MEMORY_ENCRYPT_OP that can take a struct,
and put the new op to work by including the VMSA features as a field of the
struct. The existing KVM_SEV_INIT and KVM_SEV_ES_INIT use the full set of
supported VMSA features for backwards compatibility.
The struct also includes the usual bells and whistles for future
extensibility: a flags field that must be zero for now, and some padding
at the end.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
.../virt/kvm/x86/amd-memory-encryption.rst | 40 ++++++++++++--
arch/x86/include/uapi/asm/kvm.h | 9 ++++
arch/x86/kvm/svm/sev.c | 53 ++++++++++++++++---
3 files changed, 92 insertions(+), 10 deletions(-)
diff --git a/Documentation/virt/kvm/x86/amd-memory-encryption.rst b/Documentation/virt/kvm/x86/amd-memory-encryption.rst
index 2ea648e4c97a..3381556d596d 100644
--- a/Documentation/virt/kvm/x86/amd-memory-encryption.rst
+++ b/Documentation/virt/kvm/x86/amd-memory-encryption.rst
@@ -76,15 +76,49 @@ are defined in ``<linux/psp-dev.h>``.
KVM implements the following commands to support common lifecycle events of SEV
guests, such as launching, running, snapshotting, migrating and decommissioning.
-1. KVM_SEV_INIT
----------------
+1. KVM_SEV_INIT2
+----------------
-The KVM_SEV_INIT command is used by the hypervisor to initialize the SEV platform
+The KVM_SEV_INIT2 command is used by the hypervisor to initialize the SEV platform
context. In a typical workflow, this command should be the first command issued.
+For this command to be accepted, either KVM_X86_SEV_VM or KVM_X86_SEV_ES_VM
+must have been passed to the KVM_CREATE_VM ioctl. A virtual machine created
+with those machine types in turn cannot be run until KVM_SEV_INIT2 is invoked.
+
+Parameters: struct kvm_sev_init (in)
Returns: 0 on success, -negative on error
+::
+
+ struct kvm_sev_init {
+ __u64 vmsa_features; /* initial value of features field in VMSA */
+ __u32 flags; /* must be 0 */
+ __u32 pad[9];
+ };
+
+It is an error if the hypervisor does not support any of the bits that
+are set in ``flags`` or ``vmsa_features``. ``vmsa_features`` must be
+0 for SEV virtual machines, as they do not have a VMSA.
+
+This command replaces the deprecated KVM_SEV_INIT and KVM_SEV_ES_INIT commands.
+The commands did not have any parameters (the ```data``` field was unused) and
+only work for the KVM_X86_DEFAULT_VM machine type (0).
+
+They behave as if:
+
+* the VM type is KVM_X86_SEV_VM for KVM_SEV_INIT, or KVM_X86_SEV_ES_VM for
+ KVM_SEV_ES_INIT
+
+* the ``flags`` and ``vmsa_features`` fields of ``struct kvm_sev_init`` are
+ set to zero
+
+If the ``KVM_X86_SEV_VMSA_FEATURES`` attribute does not exist, the hypervisor only
+supports KVM_SEV_INIT and KVM_SEV_ES_INIT. In that case, note that KVM_SEV_ES_INIT
+might set the debug swap VMSA feature (bit 5) depending on the value of the
+``debug_swap`` parameter of ``kvm-amd.ko``.
+
2. KVM_SEV_LAUNCH_START
-----------------------
diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index ab609adacb11..72ad5ace118d 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -694,6 +694,9 @@ enum sev_cmd_id {
/* Guest Migration Extension */
KVM_SEV_SEND_CANCEL,
+ /* Second time is the charm; improved versions of the above ioctls. */
+ KVM_SEV_INIT2,
+
KVM_SEV_NR_MAX,
};
@@ -705,6 +708,12 @@ struct kvm_sev_cmd {
__u32 sev_fd;
};
+struct kvm_sev_init {
+ __u64 vmsa_features;
+ __u32 flags;
+ __u32 pad[9];
+};
+
struct kvm_sev_launch_start {
__u32 handle;
__u32 policy;
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 3517d6736c93..2f20270be93b 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -243,27 +243,31 @@ static void sev_unbind_asid(struct kvm *kvm, unsigned int handle)
sev_decommission(handle);
}
-static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
+static int __sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp,
+ struct kvm_sev_init *data,
+ unsigned long vm_type)
{
struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
struct sev_platform_init_args init_args = {0};
+ bool es_active = vm_type != KVM_X86_SEV_VM;
+ u64 valid_vmsa_features = es_active ? sev_supported_vmsa_features : 0;
int ret;
if (kvm->created_vcpus)
return -EINVAL;
- if (kvm->arch.vm_type != KVM_X86_DEFAULT_VM)
+ if (data->flags)
+ return -EINVAL;
+
+ if (data->vmsa_features & ~valid_vmsa_features)
return -EINVAL;
if (unlikely(sev->active))
return -EINVAL;
sev->active = true;
- sev->es_active = argp->id == KVM_SEV_ES_INIT;
- sev->vmsa_features = sev_supported_vmsa_features;
- if (sev_supported_vmsa_features)
- pr_warn_once("Enabling DebugSwap with KVM_SEV_ES_INIT. "
- "This will not work starting with Linux 6.10\n");
+ sev->es_active = es_active;
+ sev->vmsa_features = data->vmsa_features;
ret = sev_asid_new(sev);
if (ret)
@@ -293,6 +297,38 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
return ret;
}
+static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
+{
+ struct kvm_sev_init data = {
+ .vmsa_features = 0,
+ };
+ unsigned long vm_type;
+
+ if (kvm->arch.vm_type != KVM_X86_DEFAULT_VM)
+ return -EINVAL;
+
+ vm_type = (argp->id == KVM_SEV_INIT ? KVM_X86_SEV_VM : KVM_X86_SEV_ES_VM);
+ return __sev_guest_init(kvm, argp, &data, vm_type);
+}
+
+static int sev_guest_init2(struct kvm *kvm, struct kvm_sev_cmd *argp)
+{
+ struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+ struct kvm_sev_init data;
+
+ if (!sev->need_init)
+ return -EINVAL;
+
+ if (kvm->arch.vm_type != KVM_X86_SEV_VM &&
+ kvm->arch.vm_type != KVM_X86_SEV_ES_VM)
+ return -EINVAL;
+
+ if (copy_from_user(&data, u64_to_user_ptr(argp->data), sizeof(data)))
+ return -EFAULT;
+
+ return __sev_guest_init(kvm, argp, &data, kvm->arch.vm_type);
+}
+
static int sev_bind_asid(struct kvm *kvm, unsigned int handle, int *error)
{
unsigned int asid = sev_get_asid(kvm);
@@ -1960,6 +1996,9 @@ int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
case KVM_SEV_INIT:
r = sev_guest_init(kvm, &sev_cmd);
break;
+ case KVM_SEV_INIT2:
+ r = sev_guest_init2(kvm, &sev_cmd);
+ break;
case KVM_SEV_LAUNCH_START:
r = sev_launch_start(kvm, &sev_cmd);
break;
--
2.43.0
next prev parent reply other threads:[~2024-04-04 12:13 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-04 12:13 [PATCH v5 00/17] KVM: SEV: allow customizing VMSA features Paolo Bonzini
2024-04-04 12:13 ` [PATCH v5 01/17] KVM: SVM: Invert handling of SEV and SEV_ES feature flags Paolo Bonzini
2024-04-04 12:13 ` [PATCH v5 02/17] KVM: SVM: Compile sev.c if and only if CONFIG_KVM_AMD_SEV=y Paolo Bonzini
2024-04-04 12:13 ` [PATCH v5 03/17] KVM: x86: use u64_to_user_ptr() Paolo Bonzini
2024-04-04 12:13 ` [PATCH v5 04/17] KVM: introduce new vendor op for KVM_GET_DEVICE_ATTR Paolo Bonzini
2024-04-04 21:30 ` Isaku Yamahata
2024-04-04 12:13 ` [PATCH v5 05/17] KVM: SEV: publish supported VMSA features Paolo Bonzini
2024-04-04 21:32 ` Isaku Yamahata
2024-04-04 12:13 ` [PATCH v5 06/17] KVM: SEV: store VMSA features in kvm_sev_info Paolo Bonzini
2024-04-04 12:13 ` [PATCH v5 07/17] KVM: x86: add fields to struct kvm_arch for CoCo features Paolo Bonzini
2024-04-04 21:39 ` Isaku Yamahata
2024-04-05 23:01 ` Edgecombe, Rick P
2024-04-09 1:21 ` Sean Christopherson
2024-04-09 14:01 ` Edgecombe, Rick P
2024-04-09 14:43 ` Paolo Bonzini
2024-04-09 15:26 ` Sean Christopherson
2024-05-07 23:01 ` Edgecombe, Rick P
2024-05-08 0:21 ` Sean Christopherson
2024-05-08 1:19 ` Edgecombe, Rick P
2024-05-08 14:38 ` Sean Christopherson
2024-05-08 15:04 ` Edgecombe, Rick P
2024-04-04 12:13 ` [PATCH v5 08/17] KVM: x86: Add supported_vm_types to kvm_caps Paolo Bonzini
2024-04-04 12:13 ` [PATCH v5 09/17] KVM: SEV: introduce to_kvm_sev_info Paolo Bonzini
2024-04-04 12:13 ` [PATCH v5 10/17] KVM: SEV: define VM types for SEV and SEV-ES Paolo Bonzini
2024-04-04 12:13 ` [PATCH v5 11/17] KVM: SEV: sync FPU and AVX state at LAUNCH_UPDATE_VMSA time Paolo Bonzini
2024-04-04 12:13 ` Paolo Bonzini [this message]
2024-04-04 12:13 ` [PATCH v5 13/17] KVM: SEV: allow SEV-ES DebugSwap again Paolo Bonzini
2024-04-04 12:13 ` [PATCH v5 14/17] selftests: kvm: add tests for KVM_SEV_INIT2 Paolo Bonzini
2024-04-04 12:13 ` [PATCH v5 15/17] selftests: kvm: switch to using KVM_X86_*_VM Paolo Bonzini
2024-04-04 12:13 ` [PATCH v5 16/17] selftests: kvm: split "launch" phase of SEV VM creation Paolo Bonzini
2024-04-04 12:13 ` [PATCH v5 17/17] selftests: kvm: add test for transferring FPU state into VMSA Paolo Bonzini
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