linux-kernel - Re: [PATCH v6 05/14] KVM: SVM: Add KVM_SEV_RECEIVE_UPDATE

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Date:   Thu, 2 Apr 2020 17:29:43 -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 05/14] KVM: SVM: Add KVM_SEV_RECEIVE_UPDATE_DATA
 command

On 2020-03-30 06:21:20 +0000, Ashish Kalra wrote:
> From: Brijesh Singh <Brijesh.Singh@....com>
> 
> The command is used for copying the incoming buffer into the
> SEV guest memory space.
> 
> 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>

> ---
>  .../virt/kvm/amd-memory-encryption.rst        | 24 ++++++
>  arch/x86/kvm/svm.c                            | 79 +++++++++++++++++++
>  include/uapi/linux/kvm.h                      |  9 +++
>  3 files changed, 112 insertions(+)
> 
> diff --git a/Documentation/virt/kvm/amd-memory-encryption.rst b/Documentation/virt/kvm/amd-memory-encryption.rst
> index ef1f1f3a5b40..554aa33a99cc 100644
> --- a/Documentation/virt/kvm/amd-memory-encryption.rst
> +++ b/Documentation/virt/kvm/amd-memory-encryption.rst
> @@ -351,6 +351,30 @@ On success, the 'handle' field contains a new handle and on error, a negative va
>  
>  For more details, see SEV spec Section 6.12.
>  
> +14. KVM_SEV_RECEIVE_UPDATE_DATA
> +----------------------------
> +
> +The KVM_SEV_RECEIVE_UPDATE_DATA command can be used by the hypervisor to copy
> +the incoming buffers into the guest memory region with encryption context
> +created during the KVM_SEV_RECEIVE_START.
> +
> +Parameters (in): struct kvm_sev_receive_update_data
> +
> +Returns: 0 on success, -negative on error
> +
> +::
> +
> +        struct kvm_sev_launch_receive_update_data {
> +                __u64 hdr_uaddr;        /* userspace address containing the packet header */
> +                __u32 hdr_len;
> +
> +                __u64 guest_uaddr;      /* the destination guest memory region */
> +                __u32 guest_len;
> +
> +                __u64 trans_uaddr;      /* the incoming buffer memory region  */
> +                __u32 trans_len;
> +        };
> +
>  References
>  ==========
>  
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 038b47685733..5fc5355536d7 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -7497,6 +7497,82 @@ static int sev_receive_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
>  	return ret;
>  }
>  
> +static int sev_receive_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
> +{
> +	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
> +	struct kvm_sev_receive_update_data params;
> +	struct sev_data_receive_update_data *data;
> +	void *hdr = NULL, *trans = NULL;
> +	struct page **guest_page;
> +	unsigned long n;
> +	int ret, offset;
> +
> +	if (!sev_guest(kvm))
> +		return -EINVAL;
> +
> +	if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data,
> +			sizeof(struct kvm_sev_receive_update_data)))
> +		return -EFAULT;
> +
> +	if (!params.hdr_uaddr || !params.hdr_len ||
> +	    !params.guest_uaddr || !params.guest_len ||
> +	    !params.trans_uaddr || !params.trans_len)
> +		return -EINVAL;
> +
> +	/* Check if we are crossing the page boundary */
> +	offset = params.guest_uaddr & (PAGE_SIZE - 1);
> +	if ((params.guest_len + offset > PAGE_SIZE))
> +		return -EINVAL;
> +
> +	hdr = psp_copy_user_blob(params.hdr_uaddr, params.hdr_len);
> +	if (IS_ERR(hdr))
> +		return PTR_ERR(hdr);
> +
> +	trans = psp_copy_user_blob(params.trans_uaddr, params.trans_len);
> +	if (IS_ERR(trans)) {
> +		ret = PTR_ERR(trans);
> +		goto e_free_hdr;
> +	}
> +
> +	ret = -ENOMEM;
> +	data = kzalloc(sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		goto e_free_trans;
> +
> +	data->hdr_address = __psp_pa(hdr);
> +	data->hdr_len = params.hdr_len;
> +	data->trans_address = __psp_pa(trans);
> +	data->trans_len = params.trans_len;
> +
> +	/* Pin guest memory */
> +	ret = -EFAULT;
> +	guest_page = sev_pin_memory(kvm, params.guest_uaddr & PAGE_MASK,
> +				    PAGE_SIZE, &n, 0);
> +	if (!guest_page)
> +		goto e_free;
> +
> +	/* The RECEIVE_UPDATE_DATA command requires C-bit to be always set. */
> +	data->guest_address = (page_to_pfn(guest_page[0]) << PAGE_SHIFT) +
> +				offset;
> +	data->guest_address |= sev_me_mask;
> +	data->guest_len = params.guest_len;
> +	data->handle = sev->handle;
> +
> +	ret = sev_issue_cmd(kvm, SEV_CMD_RECEIVE_UPDATE_DATA, data,
> +				&argp->error);
> +
> +	sev_unpin_memory(kvm, guest_page, n);
> +
> +e_free:
> +	kfree(data);
> +e_free_trans:
> +	kfree(trans);
> +e_free_hdr:
> +	kfree(hdr);
> +
> +	return ret;
> +}
> +
>  static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
>  {
>  	struct kvm_sev_cmd sev_cmd;
> @@ -7553,6 +7629,9 @@ static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
>  	case KVM_SEV_RECEIVE_START:
>  		r = sev_receive_start(kvm, &sev_cmd);
>  		break;
> +	case KVM_SEV_RECEIVE_UPDATE_DATA:
> +		r = sev_receive_update_data(kvm, &sev_cmd);
> +		break;
>  	default:
>  		r = -EINVAL;
>  		goto out;
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 74764b9db5fa..4e80c57a3182 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1588,6 +1588,15 @@ struct kvm_sev_receive_start {
>  	__u32 session_len;
>  };
>  
> +struct kvm_sev_receive_update_data {
> +	__u64 hdr_uaddr;
> +	__u32 hdr_len;
> +	__u64 guest_uaddr;
> +	__u32 guest_len;
> +	__u64 trans_uaddr;
> +	__u32 trans_len;
> +};
> +
>  #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)
> -- 
> 2.17.1
>