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    Subject[PATCH v7 12/18] KVM: x86: Introduce KVM_SET_PAGE_ENC_BITMAP ioctl
    Date
    From: Brijesh Singh <Brijesh.Singh@amd.com>

    The ioctl can be used to set page encryption bitmap for an
    incoming guest.

    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: Paolo Bonzini <pbonzini@redhat.com>
    Cc: "Radim Krčmář" <rkrcmar@redhat.com>
    Cc: Joerg Roedel <joro@8bytes.org>
    Cc: Borislav Petkov <bp@suse.de>
    Cc: Tom Lendacky <thomas.lendacky@amd.com>
    Cc: x86@kernel.org
    Cc: kvm@vger.kernel.org
    Cc: linux-kernel@vger.kernel.org
    Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com>
    Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
    Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
    ---
    Documentation/virt/kvm/api.rst | 44 ++++++++++++++++++++++++++++++
    arch/x86/include/asm/kvm_host.h | 2 ++
    arch/x86/kvm/svm/sev.c | 48 +++++++++++++++++++++++++++++++++
    arch/x86/kvm/svm/svm.c | 1 +
    arch/x86/kvm/svm/svm.h | 1 +
    arch/x86/kvm/x86.c | 12 +++++++++
    include/uapi/linux/kvm.h | 1 +
    7 files changed, 109 insertions(+)

    diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
    index e2f0dd105b5c..56c934db2a96 100644
    --- a/Documentation/virt/kvm/api.rst
    +++ b/Documentation/virt/kvm/api.rst
    @@ -4663,6 +4663,28 @@ or shared. The bitmap can be used during the guest migration, if the page
    is private then userspace need to use SEV migration commands to transmit
    the page.

    +4.126 KVM_SET_PAGE_ENC_BITMAP (vm ioctl)
    +---------------------------------------
    +
    +:Capability: basic
    +:Architectures: x86
    +:Type: vm ioctl
    +:Parameters: struct kvm_page_enc_bitmap (in/out)
    +:Returns: 0 on success, -1 on error
    +
    +/* for KVM_SET_PAGE_ENC_BITMAP */
    +struct kvm_page_enc_bitmap {
    + __u64 start_gfn;
    + __u64 num_pages;
    + union {
    + void __user *enc_bitmap; /* one bit per page */
    + __u64 padding2;
    + };
    +};
    +
    +During the guest live migration the outgoing guest exports its page encryption
    +bitmap, the KVM_SET_PAGE_ENC_BITMAP can be used to build the page encryption
    +bitmap for an incoming guest.

    4.125 KVM_S390_PV_COMMAND
    -------------------------
    @@ -4717,6 +4739,28 @@ KVM_PV_VM_VERIFY
    Verify the integrity of the unpacked image. Only if this succeeds,
    KVM is allowed to start protected VCPUs.

    +4.126 KVM_SET_PAGE_ENC_BITMAP (vm ioctl)
    +---------------------------------------
    +
    +:Capability: basic
    +:Architectures: x86
    +:Type: vm ioctl
    +:Parameters: struct kvm_page_enc_bitmap (in/out)
    +:Returns: 0 on success, -1 on error
    +
    +/* for KVM_SET_PAGE_ENC_BITMAP */
    +struct kvm_page_enc_bitmap {
    + __u64 start_gfn;
    + __u64 num_pages;
    + union {
    + void __user *enc_bitmap; /* one bit per page */
    + __u64 padding2;
    + };
    +};
    +
    +During the guest live migration the outgoing guest exports its page encryption
    +bitmap, the KVM_SET_PAGE_ENC_BITMAP can be used to build the page encryption
    +bitmap for an incoming guest.

    5. The kvm_run structure
    ========================
    diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
    index 9e428befb6a4..fc74144d5ab0 100644
    --- a/arch/x86/include/asm/kvm_host.h
    +++ b/arch/x86/include/asm/kvm_host.h
    @@ -1258,6 +1258,8 @@ struct kvm_x86_ops {
    unsigned long sz, unsigned long mode);
    int (*get_page_enc_bitmap)(struct kvm *kvm,
    struct kvm_page_enc_bitmap *bmap);
    + int (*set_page_enc_bitmap)(struct kvm *kvm,
    + struct kvm_page_enc_bitmap *bmap);
    };

    struct kvm_x86_init_ops {
    diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
    index 73bbbffb3487..64ff51ec4933 100644
    --- a/arch/x86/kvm/svm/sev.c
    +++ b/arch/x86/kvm/svm/sev.c
    @@ -1504,6 +1504,54 @@ int svm_get_page_enc_bitmap(struct kvm *kvm,
    return ret;
    }

    +int svm_set_page_enc_bitmap(struct kvm *kvm,
    + struct kvm_page_enc_bitmap *bmap)
    +{
    + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
    + unsigned long gfn_start, gfn_end;
    + unsigned long *bitmap;
    + unsigned long sz;
    + int ret;
    +
    + if (!sev_guest(kvm))
    + return -ENOTTY;
    + /* special case of resetting the complete bitmap */
    + if (!bmap->enc_bitmap) {
    + mutex_lock(&kvm->lock);
    + /* by default all pages are marked encrypted */
    + if (sev->page_enc_bmap_size)
    + bitmap_fill(sev->page_enc_bmap, sev->page_enc_bmap_size);
    + mutex_unlock(&kvm->lock);
    + return 0;
    + }
    +
    + gfn_start = bmap->start_gfn;
    + gfn_end = gfn_start + bmap->num_pages;
    +
    + sz = ALIGN(bmap->num_pages, BITS_PER_LONG) / 8;
    + bitmap = kmalloc(sz, GFP_KERNEL);
    + if (!bitmap)
    + return -ENOMEM;
    +
    + ret = -EFAULT;
    + if (copy_from_user(bitmap, bmap->enc_bitmap, sz))
    + goto out;
    +
    + mutex_lock(&kvm->lock);
    + ret = sev_resize_page_enc_bitmap(kvm, gfn_end);
    + if (ret)
    + goto unlock;
    +
    + bitmap_copy(sev->page_enc_bmap + BIT_WORD(gfn_start), bitmap, (gfn_end - gfn_start));
    +
    + ret = 0;
    +unlock:
    + mutex_unlock(&kvm->lock);
    +out:
    + kfree(bitmap);
    + return ret;
    +}
    +
    int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
    {
    struct kvm_sev_cmd sev_cmd;
    diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
    index 588709a9f68e..501e82f5593c 100644
    --- a/arch/x86/kvm/svm/svm.c
    +++ b/arch/x86/kvm/svm/svm.c
    @@ -4017,6 +4017,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {

    .page_enc_status_hc = svm_page_enc_status_hc,
    .get_page_enc_bitmap = svm_get_page_enc_bitmap,
    + .set_page_enc_bitmap = svm_set_page_enc_bitmap,
    };

    static struct kvm_x86_init_ops svm_init_ops __initdata = {
    diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
    index f087fa7b380c..2ebdcce50312 100644
    --- a/arch/x86/kvm/svm/svm.h
    +++ b/arch/x86/kvm/svm/svm.h
    @@ -405,6 +405,7 @@ int nested_svm_exit_special(struct vcpu_svm *svm);
    int svm_page_enc_status_hc(struct kvm *kvm, unsigned long gpa,
    unsigned long npages, unsigned long enc);
    int svm_get_page_enc_bitmap(struct kvm *kvm, struct kvm_page_enc_bitmap *bmap);
    +int svm_set_page_enc_bitmap(struct kvm *kvm, struct kvm_page_enc_bitmap *bmap);

    /* avic.c */

    diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
    index 937797cfaf9a..c4166d7a0493 100644
    --- a/arch/x86/kvm/x86.c
    +++ b/arch/x86/kvm/x86.c
    @@ -5220,6 +5220,18 @@ long kvm_arch_vm_ioctl(struct file *filp,
    r = kvm_x86_ops.get_page_enc_bitmap(kvm, &bitmap);
    break;
    }
    + case KVM_SET_PAGE_ENC_BITMAP: {
    + struct kvm_page_enc_bitmap bitmap;
    +
    + r = -EFAULT;
    + if (copy_from_user(&bitmap, argp, sizeof(bitmap)))
    + goto out;
    +
    + r = -ENOTTY;
    + if (kvm_x86_ops.set_page_enc_bitmap)
    + r = kvm_x86_ops.set_page_enc_bitmap(kvm, &bitmap);
    + break;
    + }
    default:
    r = -ENOTTY;
    }
    diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
    index af62f2afaa5d..2798b17484d0 100644
    --- a/include/uapi/linux/kvm.h
    +++ b/include/uapi/linux/kvm.h
    @@ -1529,6 +1529,7 @@ struct kvm_pv_cmd {
    #define KVM_S390_PV_COMMAND _IOWR(KVMIO, 0xc5, struct kvm_pv_cmd)

    #define KVM_GET_PAGE_ENC_BITMAP _IOW(KVMIO, 0xc6, struct kvm_page_enc_bitmap)
    +#define KVM_SET_PAGE_ENC_BITMAP _IOW(KVMIO, 0xc7, struct kvm_page_enc_bitmap)

    /* Secure Encrypted Virtualization command */
    enum sev_cmd_id {
    --
    2.17.1
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