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    Subject[PATCH Part2 v6 24/49] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_START command
    Date
    From: Brijesh Singh <brijesh.singh@amd.com>

    KVM_SEV_SNP_LAUNCH_START begins the launch process for an SEV-SNP guest.
    The command initializes a cryptographic digest context used to construct
    the measurement of the guest. If the guest is expected to be migrated,
    the command also binds a migration agent (MA) to the guest.

    For more information see the SEV-SNP specification.

    Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
    ---
    .../virt/kvm/x86/amd-memory-encryption.rst | 24 ++++
    arch/x86/kvm/svm/sev.c | 115 +++++++++++++++++-
    arch/x86/kvm/svm/svm.h | 1 +
    include/uapi/linux/kvm.h | 10 ++
    4 files changed, 147 insertions(+), 3 deletions(-)

    diff --git a/Documentation/virt/kvm/x86/amd-memory-encryption.rst b/Documentation/virt/kvm/x86/amd-memory-encryption.rst
    index 903023f524af..878711f2dca6 100644
    --- a/Documentation/virt/kvm/x86/amd-memory-encryption.rst
    +++ b/Documentation/virt/kvm/x86/amd-memory-encryption.rst
    @@ -462,6 +462,30 @@ The flags bitmap is defined as::
    If the specified flags is not supported then return -EOPNOTSUPP, and the supported
    flags are returned.

    +19. KVM_SNP_LAUNCH_START
    +------------------------
    +
    +The KVM_SNP_LAUNCH_START command is used for creating the memory encryption
    +context for the SEV-SNP guest. To create the encryption context, user must
    +provide a guest policy, migration agent (if any) and guest OS visible
    +workarounds value as defined SEV-SNP specification.
    +
    +Parameters (in): struct kvm_snp_launch_start
    +
    +Returns: 0 on success, -negative on error
    +
    +::
    +
    + struct kvm_sev_snp_launch_start {
    + __u64 policy; /* Guest policy to use. */
    + __u64 ma_uaddr; /* userspace address of migration agent */
    + __u8 ma_en; /* 1 if the migtation agent is enabled */
    + __u8 imi_en; /* set IMI to 1. */
    + __u8 gosvw[16]; /* guest OS visible workarounds */
    + };
    +
    +See the SEV-SNP specification for further detail on the launch input.
    +
    References
    ==========

    diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
    index 813bda7f7b55..9e6fc7a94ed7 100644
    --- a/arch/x86/kvm/svm/sev.c
    +++ b/arch/x86/kvm/svm/sev.c
    @@ -21,6 +21,7 @@
    #include <asm/pkru.h>
    #include <asm/trapnr.h>
    #include <asm/fpu/xcr.h>
    +#include <asm/sev.h>

    #include "x86.h"
    #include "svm.h"
    @@ -73,6 +74,8 @@ static unsigned int nr_asids;
    static unsigned long *sev_asid_bitmap;
    static unsigned long *sev_reclaim_asid_bitmap;

    +static int snp_decommission_context(struct kvm *kvm);
    +
    struct enc_region {
    struct list_head list;
    unsigned long npages;
    @@ -98,12 +101,17 @@ static int sev_flush_asids(int min_asid, int max_asid)
    down_write(&sev_deactivate_lock);

    wbinvd_on_all_cpus();
    - ret = sev_guest_df_flush(&error);
    +
    + if (sev_snp_enabled)
    + ret = snp_guest_df_flush(&error);
    + else
    + ret = sev_guest_df_flush(&error);

    up_write(&sev_deactivate_lock);

    if (ret)
    - pr_err("SEV: DF_FLUSH failed, ret=%d, error=%#x\n", ret, error);
    + pr_err("SEV%s: DF_FLUSH failed, ret=%d, error=%#x\n",
    + sev_snp_enabled ? "-SNP" : "", ret, error);

    return ret;
    }
    @@ -1825,6 +1833,74 @@ int sev_vm_move_enc_context_from(struct kvm *kvm, unsigned int source_fd)
    return ret;
    }

    +static void *snp_context_create(struct kvm *kvm, struct kvm_sev_cmd *argp)
    +{
    + struct sev_data_snp_gctx_create data = {};
    + void *context;
    + int rc;
    +
    + /* Allocate memory for context page */
    + context = snp_alloc_firmware_page(GFP_KERNEL_ACCOUNT);
    + if (!context)
    + return NULL;
    +
    + data.gctx_paddr = __psp_pa(context);
    + rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_GCTX_CREATE, &data, &argp->error);
    + if (rc) {
    + snp_free_firmware_page(context);
    + return NULL;
    + }
    +
    + return context;
    +}
    +
    +static int snp_bind_asid(struct kvm *kvm, int *error)
    +{
    + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
    + struct sev_data_snp_activate data = {0};
    +
    + data.gctx_paddr = __psp_pa(sev->snp_context);
    + data.asid = sev_get_asid(kvm);
    + return sev_issue_cmd(kvm, SEV_CMD_SNP_ACTIVATE, &data, error);
    +}
    +
    +static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
    +{
    + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
    + struct sev_data_snp_launch_start start = {0};
    + struct kvm_sev_snp_launch_start params;
    + int rc;
    +
    + if (!sev_snp_guest(kvm))
    + return -ENOTTY;
    +
    + if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data, sizeof(params)))
    + return -EFAULT;
    +
    + sev->snp_context = snp_context_create(kvm, argp);
    + if (!sev->snp_context)
    + return -ENOTTY;
    +
    + start.gctx_paddr = __psp_pa(sev->snp_context);
    + start.policy = params.policy;
    + memcpy(start.gosvw, params.gosvw, sizeof(params.gosvw));
    + rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_LAUNCH_START, &start, &argp->error);
    + if (rc)
    + goto e_free_context;
    +
    + sev->fd = argp->sev_fd;
    + rc = snp_bind_asid(kvm, &argp->error);
    + if (rc)
    + goto e_free_context;
    +
    + return 0;
    +
    +e_free_context:
    + snp_decommission_context(kvm);
    +
    + return rc;
    +}
    +
    int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
    {
    struct kvm_sev_cmd sev_cmd;
    @@ -1915,6 +1991,9 @@ int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
    case KVM_SEV_RECEIVE_FINISH:
    r = sev_receive_finish(kvm, &sev_cmd);
    break;
    + case KVM_SEV_SNP_LAUNCH_START:
    + r = snp_launch_start(kvm, &sev_cmd);
    + break;
    default:
    r = -EINVAL;
    goto out;
    @@ -2106,6 +2185,28 @@ int sev_vm_copy_enc_context_from(struct kvm *kvm, unsigned int source_fd)
    return ret;
    }

    +static int snp_decommission_context(struct kvm *kvm)
    +{
    + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
    + struct sev_data_snp_decommission data = {};
    + int ret;
    +
    + /* If context is not created then do nothing */
    + if (!sev->snp_context)
    + return 0;
    +
    + data.gctx_paddr = __sme_pa(sev->snp_context);
    + ret = snp_guest_decommission(&data, NULL);
    + if (WARN_ONCE(ret, "failed to release guest context"))
    + return ret;
    +
    + /* free the context page now */
    + snp_free_firmware_page(sev->snp_context);
    + sev->snp_context = NULL;
    +
    + return 0;
    +}
    +
    void sev_vm_destroy(struct kvm *kvm)
    {
    struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
    @@ -2147,7 +2248,15 @@ void sev_vm_destroy(struct kvm *kvm)
    }
    }

    - sev_unbind_asid(kvm, sev->handle);
    + if (sev_snp_guest(kvm)) {
    + if (snp_decommission_context(kvm)) {
    + WARN_ONCE(1, "Failed to free SNP guest context, leaking asid!\n");
    + return;
    + }
    + } else {
    + sev_unbind_asid(kvm, sev->handle);
    + }
    +
    sev_asid_free(sev);
    }

    diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
    index 2f45589ee596..71c011af098e 100644
    --- a/arch/x86/kvm/svm/svm.h
    +++ b/arch/x86/kvm/svm/svm.h
    @@ -91,6 +91,7 @@ struct kvm_sev_info {
    struct misc_cg *misc_cg; /* For misc cgroup accounting */
    atomic_t migration_in_progress;
    u64 snp_init_flags;
    + void *snp_context; /* SNP guest context page */
    };

    struct kvm_svm {
    diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
    index 0f912cefc544..0cb119d66ae5 100644
    --- a/include/uapi/linux/kvm.h
    +++ b/include/uapi/linux/kvm.h
    @@ -1812,6 +1812,7 @@ enum sev_cmd_id {

    /* SNP specific commands */
    KVM_SEV_SNP_INIT,
    + KVM_SEV_SNP_LAUNCH_START,

    KVM_SEV_NR_MAX,
    };
    @@ -1919,6 +1920,15 @@ struct kvm_snp_init {
    __u64 flags;
    };

    +struct kvm_sev_snp_launch_start {
    + __u64 policy;
    + __u64 ma_uaddr;
    + __u8 ma_en;
    + __u8 imi_en;
    + __u8 gosvw[16];
    + __u8 pad[6];
    +};
    +
    #define KVM_DEV_ASSIGN_ENABLE_IOMMU (1 << 0)
    #define KVM_DEV_ASSIGN_PCI_2_3 (1 << 1)
    #define KVM_DEV_ASSIGN_MASK_INTX (1 << 2)
    --
    2.25.1
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