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Date: Fri, 3 Apr 2020 16:46:32 -0500
From: Venu Busireddy <venu.busireddy@...cle.com>
To: Ashish Kalra <Ashish.Kalra@....com>
Cc: pbonzini@...hat.com, tglx@...utronix.de, mingo@...hat.com,
hpa@...or.com, joro@...tes.org, bp@...e.de,
thomas.lendacky@....com, x86@...nel.org, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org, rientjes@...gle.com,
srutherford@...gle.com, luto@...nel.org, brijesh.singh@....com
Subject: Re: [PATCH v6 11/14] KVM: x86: Introduce KVM_SET_PAGE_ENC_BITMAP
ioctl
On 2020-03-30 06:22:55 +0000, Ashish Kalra wrote:
> From: Brijesh Singh <Brijesh.Singh@....com>
>
> The ioctl can be used to set page encryption bitmap for an
> incoming guest.
>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: "H. Peter Anvin" <hpa@...or.com>
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: "Radim Krčmář" <rkrcmar@...hat.com>
> Cc: Joerg Roedel <joro@...tes.org>
> Cc: Borislav Petkov <bp@...e.de>
> Cc: Tom Lendacky <thomas.lendacky@....com>
> Cc: x86@...nel.org
> Cc: kvm@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
> Signed-off-by: Ashish Kalra <ashish.kalra@....com>
Reviewed-by: Venu Busireddy <venu.busireddy@...cle.com>
> ---
> Documentation/virt/kvm/api.rst | 22 +++++++++++++++++
> arch/x86/include/asm/kvm_host.h | 2 ++
> arch/x86/kvm/svm.c | 42 +++++++++++++++++++++++++++++++++
> arch/x86/kvm/x86.c | 12 ++++++++++
> include/uapi/linux/kvm.h | 1 +
> 5 files changed, 79 insertions(+)
>
> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
> index 8ad800ebb54f..4d1004a154f6 100644
> --- a/Documentation/virt/kvm/api.rst
> +++ b/Documentation/virt/kvm/api.rst
> @@ -4675,6 +4675,28 @@ 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.
>
> 5. The kvm_run structure
> ========================
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 27e43e3ec9d8..d30f770aaaea 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1271,6 +1271,8 @@ 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_arch_async_pf {
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index bae783cd396a..313343a43045 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -7756,6 +7756,47 @@ static int svm_get_page_enc_bitmap(struct kvm *kvm,
> return ret;
> }
>
> +static 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, i;
> + int ret;
> +
> + if (!sev_guest(kvm))
> + return -ENOTTY;
> +
> + 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;
> +
> + i = gfn_start;
> + for_each_clear_bit_from(i, bitmap, (gfn_end - gfn_start))
> + clear_bit(i + gfn_start, sev->page_enc_bmap);
> +
> + ret = 0;
> +unlock:
> + mutex_unlock(&kvm->lock);
> +out:
> + kfree(bitmap);
> + return ret;
> +}
> +
> static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
> {
> struct kvm_sev_cmd sev_cmd;
> @@ -8161,6 +8202,7 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
>
> .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 int __init svm_init(void)
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 3c3fea4e20b5..05e953b2ec61 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -5238,6 +5238,18 @@ 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 db1ebf85e177..b4b01d47e568 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1489,6 +1489,7 @@ struct kvm_enc_region {
> #define KVM_S390_CLEAR_RESET _IO(KVMIO, 0xc4)
>
> #define KVM_GET_PAGE_ENC_BITMAP _IOW(KVMIO, 0xc5, struct kvm_page_enc_bitmap)
> +#define KVM_SET_PAGE_ENC_BITMAP _IOW(KVMIO, 0xc6, struct kvm_page_enc_bitmap)
>
> /* Secure Encrypted Virtualization command */
> enum sev_cmd_id {
> --
> 2.17.1
>
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