diff mbox series

[v6,02/14] KVM: SVM: Add KVM_SEND_UPDATE_DATA command

Message ID 7ea65c7852543a7cd4fb904db751bed859735a84.1585548051.git.ashish.kalra@amd.com (mailing list archive)
State New, archived
Headers show
Series Add AMD SEV guest live migration support | expand

Commit Message

Kalra, Ashish March 30, 2020, 6:20 a.m. UTC
From: Brijesh Singh <Brijesh.Singh@amd.com>

The command is used for encrypting the guest memory region using the encryption
context created with KVM_SEV_SEND_START.

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 : Steve Rutherford <srutherford@google.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
 .../virt/kvm/amd-memory-encryption.rst        |  24 ++++
 arch/x86/kvm/svm.c                            | 136 +++++++++++++++++-
 include/uapi/linux/kvm.h                      |   9 ++
 3 files changed, 165 insertions(+), 4 deletions(-)

Comments

Venu Busireddy April 2, 2020, 5:55 p.m. UTC | #1
On 2020-03-30 06:20:33 +0000, Ashish Kalra wrote:
> From: Brijesh Singh <Brijesh.Singh@amd.com>
> 
> The command is used for encrypting the guest memory region using the encryption
> context created with KVM_SEV_SEND_START.
> 
> 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 : Steve Rutherford <srutherford@google.com>
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
> ---
>  .../virt/kvm/amd-memory-encryption.rst        |  24 ++++
>  arch/x86/kvm/svm.c                            | 136 +++++++++++++++++-
>  include/uapi/linux/kvm.h                      |   9 ++
>  3 files changed, 165 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/virt/kvm/amd-memory-encryption.rst b/Documentation/virt/kvm/amd-memory-encryption.rst
> index 4fd34fc5c7a7..f46817ef7019 100644
> --- a/Documentation/virt/kvm/amd-memory-encryption.rst
> +++ b/Documentation/virt/kvm/amd-memory-encryption.rst
> @@ -290,6 +290,30 @@ Returns: 0 on success, -negative on error
>                  __u32 session_len;
>          };
>  
> +11. KVM_SEV_SEND_UPDATE_DATA
> +----------------------------
> +
> +The KVM_SEV_SEND_UPDATE_DATA command can be used by the hypervisor to encrypt the
> +outgoing guest memory region with the encryption context creating using
> +KVM_SEV_SEND_START.
> +
> +Parameters (in): struct kvm_sev_send_update_data
> +
> +Returns: 0 on success, -negative on error
> +
> +::
> +
> +        struct kvm_sev_launch_send_update_data {
> +                __u64 hdr_uaddr;        /* userspace address containing the packet header */
> +                __u32 hdr_len;
> +
> +                __u64 guest_uaddr;      /* the source memory region to be encrypted */
> +                __u32 guest_len;
> +
> +                __u64 trans_uaddr;      /* the destition memory region  */
> +                __u32 trans_len;
> +        };
> +
>  References
>  ==========
>  
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 63d172e974ad..8561c47cc4f9 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -428,6 +428,7 @@ static DECLARE_RWSEM(sev_deactivate_lock);
>  static DEFINE_MUTEX(sev_bitmap_lock);
>  static unsigned int max_sev_asid;
>  static unsigned int min_sev_asid;
> +static unsigned long sev_me_mask;
>  static unsigned long *sev_asid_bitmap;
>  static unsigned long *sev_reclaim_asid_bitmap;
>  #define __sme_page_pa(x) __sme_set(page_to_pfn(x) << PAGE_SHIFT)
> @@ -1232,16 +1233,22 @@ static int avic_ga_log_notifier(u32 ga_tag)
>  static __init int sev_hardware_setup(void)
>  {
>  	struct sev_user_data_status *status;
> +	u32 eax, ebx;
>  	int rc;
>  
> -	/* Maximum number of encrypted guests supported simultaneously */
> -	max_sev_asid = cpuid_ecx(0x8000001F);
> +	/*
> +	 * Query the memory encryption information.
> +	 *  EBX:  Bit 0:5 Pagetable bit position used to indicate encryption
> +	 *  (aka Cbit).
> +	 *  ECX:  Maximum number of encrypted guests supported simultaneously.
> +	 *  EDX:  Minimum ASID value that should be used for SEV guest.
> +	 */
> +	cpuid(0x8000001f, &eax, &ebx, &max_sev_asid, &min_sev_asid);
>  
>  	if (!max_sev_asid)
>  		return 1;
>  
> -	/* Minimum ASID value that should be used for SEV guest */
> -	min_sev_asid = cpuid_edx(0x8000001F);
> +	sev_me_mask = 1UL << (ebx & 0x3f);
>  
>  	/* Initialize SEV ASID bitmaps */
>  	sev_asid_bitmap = bitmap_zalloc(max_sev_asid, GFP_KERNEL);
> @@ -7274,6 +7281,124 @@ static int sev_send_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
>  	return ret;
>  }
>  
> +/* Userspace wants to query either header or trans length. */
> +static int
> +__sev_send_update_data_query_lengths(struct kvm *kvm, struct kvm_sev_cmd *argp,
> +				     struct kvm_sev_send_update_data *params)
> +{
> +	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
> +	struct sev_data_send_update_data *data;
> +	int ret;
> +
> +	data = kzalloc(sizeof(*data), GFP_KERNEL_ACCOUNT);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->handle = sev->handle;
> +	ret = sev_issue_cmd(kvm, SEV_CMD_SEND_UPDATE_DATA, data, &argp->error);
> +
> +	params->hdr_len = data->hdr_len;
> +	params->trans_len = data->trans_len;
> +
> +	if (copy_to_user((void __user *)(uintptr_t)argp->data, params,
> +			 sizeof(struct kvm_sev_send_update_data)))
> +		ret = -EFAULT;
> +
> +	kfree(data);
> +	return ret;
> +}
> +
> +static int sev_send_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
> +{
> +	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
> +	struct sev_data_send_update_data *data;
> +	struct kvm_sev_send_update_data params;
> +	void *hdr, *trans_data;
> +	struct page **guest_page;
> +	unsigned long n;
> +	int ret, offset;
> +
> +	if (!sev_guest(kvm))
> +		return -ENOTTY;
> +
> +	if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data,
> +			sizeof(struct kvm_sev_send_update_data)))
> +		return -EFAULT;
> +
> +	/* userspace wants to query either header or trans length */
> +	if (!params.trans_len || !params.hdr_len)
> +		return __sev_send_update_data_query_lengths(kvm, argp, &params);
> +
> +	if (!params.trans_uaddr || !params.guest_uaddr ||
> +	    !params.guest_len || !params.hdr_uaddr)
> +		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;
> +
> +	/* Pin guest memory */
> +	guest_page = sev_pin_memory(kvm, params.guest_uaddr & PAGE_MASK,
> +				    PAGE_SIZE, &n, 0);
> +	if (!guest_page)
> +		return -EFAULT;
> +
> +	/* allocate memory for header and transport buffer */
> +	ret = -ENOMEM;
> +	hdr = kmalloc(params.hdr_len, GFP_KERNEL_ACCOUNT);
> +	if (!hdr)
> +		goto e_unpin;
> +
> +	trans_data = kmalloc(params.trans_len, GFP_KERNEL_ACCOUNT);
> +	if (!trans_data)
> +		goto e_free_hdr;
> +
> +	data = kzalloc(sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		goto e_free_trans_data;
> +
> +	data->hdr_address = __psp_pa(hdr);
> +	data->hdr_len = params.hdr_len;
> +	data->trans_address = __psp_pa(trans_data);
> +	data->trans_len = params.trans_len;
> +
> +	/* The SEND_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_SEND_UPDATE_DATA, data, &argp->error);
> +
> +	if (ret)
> +		goto e_free;
> +
> +	/* copy transport buffer to user space */
> +	if (copy_to_user((void __user *)(uintptr_t)params.trans_uaddr,
> +			 trans_data, params.trans_len)) {
> +		ret = -EFAULT;
> +		goto e_unpin;

Shouldn't this be 

		goto e_free;
?

> +	}
> +
> +	/* Copy packet header to userspace. */
> +	ret = copy_to_user((void __user *)(uintptr_t)params.hdr_uaddr, hdr,
> +				params.hdr_len);
> +
> +e_free:
> +	kfree(data);
> +e_free_trans_data:
> +	kfree(trans_data);
> +e_free_hdr:
> +	kfree(hdr);
> +e_unpin:
> +	sev_unpin_memory(kvm, guest_page, n);
> +
> +	return ret;
> +}
> +
>  static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
>  {
>  	struct kvm_sev_cmd sev_cmd;
> @@ -7321,6 +7446,9 @@ static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
>  	case KVM_SEV_SEND_START:
>  		r = sev_send_start(kvm, &sev_cmd);
>  		break;
> +	case KVM_SEV_SEND_UPDATE_DATA:
> +		r = sev_send_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 17bef4c245e1..d9dc81bb9c55 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1570,6 +1570,15 @@ struct kvm_sev_send_start {
>  	__u32 session_len;
>  };
>  
> +struct kvm_sev_send_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
>
Krish Sadhukhan April 2, 2020, 8:13 p.m. UTC | #2
On 3/29/20 11:20 PM, Ashish Kalra wrote:
> From: Brijesh Singh <Brijesh.Singh@amd.com>
>
> The command is used for encrypting the guest memory region using the encryption
> context created with KVM_SEV_SEND_START.
>
> 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 : Steve Rutherford <srutherford@google.com>
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
> ---
>   .../virt/kvm/amd-memory-encryption.rst        |  24 ++++
>   arch/x86/kvm/svm.c                            | 136 +++++++++++++++++-
>   include/uapi/linux/kvm.h                      |   9 ++
>   3 files changed, 165 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/virt/kvm/amd-memory-encryption.rst b/Documentation/virt/kvm/amd-memory-encryption.rst
> index 4fd34fc5c7a7..f46817ef7019 100644
> --- a/Documentation/virt/kvm/amd-memory-encryption.rst
> +++ b/Documentation/virt/kvm/amd-memory-encryption.rst
> @@ -290,6 +290,30 @@ Returns: 0 on success, -negative on error
>                   __u32 session_len;
>           };
>   
> +11. KVM_SEV_SEND_UPDATE_DATA
> +----------------------------
> +
> +The KVM_SEV_SEND_UPDATE_DATA command can be used by the hypervisor to encrypt the
> +outgoing guest memory region with the encryption context creating using
> +KVM_SEV_SEND_START.
> +
> +Parameters (in): struct kvm_sev_send_update_data
> +
> +Returns: 0 on success, -negative on error
> +
> +::
> +
> +        struct kvm_sev_launch_send_update_data {
> +                __u64 hdr_uaddr;        /* userspace address containing the packet header */
> +                __u32 hdr_len;
> +
> +                __u64 guest_uaddr;      /* the source memory region to be encrypted */
> +                __u32 guest_len;
> +
> +                __u64 trans_uaddr;      /* the destition memory region  */
> +                __u32 trans_len;
> +        };
> +
>   References
>   ==========
>   
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 63d172e974ad..8561c47cc4f9 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -428,6 +428,7 @@ static DECLARE_RWSEM(sev_deactivate_lock);
>   static DEFINE_MUTEX(sev_bitmap_lock);
>   static unsigned int max_sev_asid;
>   static unsigned int min_sev_asid;
> +static unsigned long sev_me_mask;
>   static unsigned long *sev_asid_bitmap;
>   static unsigned long *sev_reclaim_asid_bitmap;
>   #define __sme_page_pa(x) __sme_set(page_to_pfn(x) << PAGE_SHIFT)
> @@ -1232,16 +1233,22 @@ static int avic_ga_log_notifier(u32 ga_tag)
>   static __init int sev_hardware_setup(void)
>   {
>   	struct sev_user_data_status *status;
> +	u32 eax, ebx;
>   	int rc;
>   
> -	/* Maximum number of encrypted guests supported simultaneously */
> -	max_sev_asid = cpuid_ecx(0x8000001F);
> +	/*
> +	 * Query the memory encryption information.
> +	 *  EBX:  Bit 0:5 Pagetable bit position used to indicate encryption
> +	 *  (aka Cbit).
> +	 *  ECX:  Maximum number of encrypted guests supported simultaneously.
> +	 *  EDX:  Minimum ASID value that should be used for SEV guest.
> +	 */
> +	cpuid(0x8000001f, &eax, &ebx, &max_sev_asid, &min_sev_asid);


Will max_sev_asid and the max number of guests supported be the same 
number always ?

>   
>   	if (!max_sev_asid)
>   		return 1;
>   
> -	/* Minimum ASID value that should be used for SEV guest */
> -	min_sev_asid = cpuid_edx(0x8000001F);
> +	sev_me_mask = 1UL << (ebx & 0x3f);
>   
>   	/* Initialize SEV ASID bitmaps */
>   	sev_asid_bitmap = bitmap_zalloc(max_sev_asid, GFP_KERNEL);
> @@ -7274,6 +7281,124 @@ static int sev_send_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
>   	return ret;
>   }
>   
> +/* Userspace wants to query either header or trans length. */
> +static int
> +__sev_send_update_data_query_lengths(struct kvm *kvm, struct kvm_sev_cmd *argp,
> +				     struct kvm_sev_send_update_data *params)
> +{
> +	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
> +	struct sev_data_send_update_data *data;
> +	int ret;
> +
> +	data = kzalloc(sizeof(*data), GFP_KERNEL_ACCOUNT);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->handle = sev->handle;
> +	ret = sev_issue_cmd(kvm, SEV_CMD_SEND_UPDATE_DATA, data, &argp->error);
> +
> +	params->hdr_len = data->hdr_len;
> +	params->trans_len = data->trans_len;
> +
> +	if (copy_to_user((void __user *)(uintptr_t)argp->data, params,
> +			 sizeof(struct kvm_sev_send_update_data)))
> +		ret = -EFAULT;
> +
> +	kfree(data);
> +	return ret;
> +}
> +
> +static int sev_send_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
> +{
> +	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
> +	struct sev_data_send_update_data *data;
> +	struct kvm_sev_send_update_data params;
> +	void *hdr, *trans_data;
> +	struct page **guest_page;
> +	unsigned long n;
> +	int ret, offset;
> +
> +	if (!sev_guest(kvm))
> +		return -ENOTTY;


Do we need to check the following conditions here ?

     "The platform must be in the PSTATE.WORKING state.
      The guest must be in the GSTATE.SUPDATE state."

> +
> +	if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data,
> +			sizeof(struct kvm_sev_send_update_data)))
> +		return -EFAULT;
> +
> +	/* userspace wants to query either header or trans length */
> +	if (!params.trans_len || !params.hdr_len)
> +		return __sev_send_update_data_query_lengths(kvm, argp, &params);
> +
> +	if (!params.trans_uaddr || !params.guest_uaddr ||
> +	    !params.guest_len || !params.hdr_uaddr)
> +		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;
> +
> +	/* Pin guest memory */
> +	guest_page = sev_pin_memory(kvm, params.guest_uaddr & PAGE_MASK,
> +				    PAGE_SIZE, &n, 0);
> +	if (!guest_page)
> +		return -EFAULT;
> +
> +	/* allocate memory for header and transport buffer */
> +	ret = -ENOMEM;
> +	hdr = kmalloc(params.hdr_len, GFP_KERNEL_ACCOUNT);
> +	if (!hdr)
> +		goto e_unpin;
> +
> +	trans_data = kmalloc(params.trans_len, GFP_KERNEL_ACCOUNT);
> +	if (!trans_data)
> +		goto e_free_hdr;
> +
> +	data = kzalloc(sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		goto e_free_trans_data;
> +
> +	data->hdr_address = __psp_pa(hdr);
> +	data->hdr_len = params.hdr_len;
> +	data->trans_address = __psp_pa(trans_data);
> +	data->trans_len = params.trans_len;
> +
> +	/* The SEND_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;

Why not name the variable 'sev_cbit_mask' instead of sev_me_mask ?

> +	data->guest_len = params.guest_len;
> +	data->handle = sev->handle;
> +
> +	ret = sev_issue_cmd(kvm, SEV_CMD_SEND_UPDATE_DATA, data, &argp->error);
> +
> +	if (ret)
> +		goto e_free;
> +
> +	/* copy transport buffer to user space */
> +	if (copy_to_user((void __user *)(uintptr_t)params.trans_uaddr,
> +			 trans_data, params.trans_len)) {
> +		ret = -EFAULT;
> +		goto e_unpin;
> +	}
> +
> +	/* Copy packet header to userspace. */
> +	ret = copy_to_user((void __user *)(uintptr_t)params.hdr_uaddr, hdr,
> +				params.hdr_len);
> +
> +e_free:
> +	kfree(data);
> +e_free_trans_data:
> +	kfree(trans_data);
> +e_free_hdr:
> +	kfree(hdr);
> +e_unpin:
> +	sev_unpin_memory(kvm, guest_page, n);
> +
> +	return ret;
> +}
> +
>   static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
>   {
>   	struct kvm_sev_cmd sev_cmd;
> @@ -7321,6 +7446,9 @@ static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
>   	case KVM_SEV_SEND_START:
>   		r = sev_send_start(kvm, &sev_cmd);
>   		break;
> +	case KVM_SEV_SEND_UPDATE_DATA:
> +		r = sev_send_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 17bef4c245e1..d9dc81bb9c55 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1570,6 +1570,15 @@ struct kvm_sev_send_start {
>   	__u32 session_len;
>   };
>   
> +struct kvm_sev_send_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)


Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
diff mbox series

Patch

diff --git a/Documentation/virt/kvm/amd-memory-encryption.rst b/Documentation/virt/kvm/amd-memory-encryption.rst
index 4fd34fc5c7a7..f46817ef7019 100644
--- a/Documentation/virt/kvm/amd-memory-encryption.rst
+++ b/Documentation/virt/kvm/amd-memory-encryption.rst
@@ -290,6 +290,30 @@  Returns: 0 on success, -negative on error
                 __u32 session_len;
         };
 
+11. KVM_SEV_SEND_UPDATE_DATA
+----------------------------
+
+The KVM_SEV_SEND_UPDATE_DATA command can be used by the hypervisor to encrypt the
+outgoing guest memory region with the encryption context creating using
+KVM_SEV_SEND_START.
+
+Parameters (in): struct kvm_sev_send_update_data
+
+Returns: 0 on success, -negative on error
+
+::
+
+        struct kvm_sev_launch_send_update_data {
+                __u64 hdr_uaddr;        /* userspace address containing the packet header */
+                __u32 hdr_len;
+
+                __u64 guest_uaddr;      /* the source memory region to be encrypted */
+                __u32 guest_len;
+
+                __u64 trans_uaddr;      /* the destition memory region  */
+                __u32 trans_len;
+        };
+
 References
 ==========
 
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 63d172e974ad..8561c47cc4f9 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -428,6 +428,7 @@  static DECLARE_RWSEM(sev_deactivate_lock);
 static DEFINE_MUTEX(sev_bitmap_lock);
 static unsigned int max_sev_asid;
 static unsigned int min_sev_asid;
+static unsigned long sev_me_mask;
 static unsigned long *sev_asid_bitmap;
 static unsigned long *sev_reclaim_asid_bitmap;
 #define __sme_page_pa(x) __sme_set(page_to_pfn(x) << PAGE_SHIFT)
@@ -1232,16 +1233,22 @@  static int avic_ga_log_notifier(u32 ga_tag)
 static __init int sev_hardware_setup(void)
 {
 	struct sev_user_data_status *status;
+	u32 eax, ebx;
 	int rc;
 
-	/* Maximum number of encrypted guests supported simultaneously */
-	max_sev_asid = cpuid_ecx(0x8000001F);
+	/*
+	 * Query the memory encryption information.
+	 *  EBX:  Bit 0:5 Pagetable bit position used to indicate encryption
+	 *  (aka Cbit).
+	 *  ECX:  Maximum number of encrypted guests supported simultaneously.
+	 *  EDX:  Minimum ASID value that should be used for SEV guest.
+	 */
+	cpuid(0x8000001f, &eax, &ebx, &max_sev_asid, &min_sev_asid);
 
 	if (!max_sev_asid)
 		return 1;
 
-	/* Minimum ASID value that should be used for SEV guest */
-	min_sev_asid = cpuid_edx(0x8000001F);
+	sev_me_mask = 1UL << (ebx & 0x3f);
 
 	/* Initialize SEV ASID bitmaps */
 	sev_asid_bitmap = bitmap_zalloc(max_sev_asid, GFP_KERNEL);
@@ -7274,6 +7281,124 @@  static int sev_send_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
 	return ret;
 }
 
+/* Userspace wants to query either header or trans length. */
+static int
+__sev_send_update_data_query_lengths(struct kvm *kvm, struct kvm_sev_cmd *argp,
+				     struct kvm_sev_send_update_data *params)
+{
+	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+	struct sev_data_send_update_data *data;
+	int ret;
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL_ACCOUNT);
+	if (!data)
+		return -ENOMEM;
+
+	data->handle = sev->handle;
+	ret = sev_issue_cmd(kvm, SEV_CMD_SEND_UPDATE_DATA, data, &argp->error);
+
+	params->hdr_len = data->hdr_len;
+	params->trans_len = data->trans_len;
+
+	if (copy_to_user((void __user *)(uintptr_t)argp->data, params,
+			 sizeof(struct kvm_sev_send_update_data)))
+		ret = -EFAULT;
+
+	kfree(data);
+	return ret;
+}
+
+static int sev_send_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
+{
+	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+	struct sev_data_send_update_data *data;
+	struct kvm_sev_send_update_data params;
+	void *hdr, *trans_data;
+	struct page **guest_page;
+	unsigned long n;
+	int ret, offset;
+
+	if (!sev_guest(kvm))
+		return -ENOTTY;
+
+	if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data,
+			sizeof(struct kvm_sev_send_update_data)))
+		return -EFAULT;
+
+	/* userspace wants to query either header or trans length */
+	if (!params.trans_len || !params.hdr_len)
+		return __sev_send_update_data_query_lengths(kvm, argp, &params);
+
+	if (!params.trans_uaddr || !params.guest_uaddr ||
+	    !params.guest_len || !params.hdr_uaddr)
+		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;
+
+	/* Pin guest memory */
+	guest_page = sev_pin_memory(kvm, params.guest_uaddr & PAGE_MASK,
+				    PAGE_SIZE, &n, 0);
+	if (!guest_page)
+		return -EFAULT;
+
+	/* allocate memory for header and transport buffer */
+	ret = -ENOMEM;
+	hdr = kmalloc(params.hdr_len, GFP_KERNEL_ACCOUNT);
+	if (!hdr)
+		goto e_unpin;
+
+	trans_data = kmalloc(params.trans_len, GFP_KERNEL_ACCOUNT);
+	if (!trans_data)
+		goto e_free_hdr;
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		goto e_free_trans_data;
+
+	data->hdr_address = __psp_pa(hdr);
+	data->hdr_len = params.hdr_len;
+	data->trans_address = __psp_pa(trans_data);
+	data->trans_len = params.trans_len;
+
+	/* The SEND_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_SEND_UPDATE_DATA, data, &argp->error);
+
+	if (ret)
+		goto e_free;
+
+	/* copy transport buffer to user space */
+	if (copy_to_user((void __user *)(uintptr_t)params.trans_uaddr,
+			 trans_data, params.trans_len)) {
+		ret = -EFAULT;
+		goto e_unpin;
+	}
+
+	/* Copy packet header to userspace. */
+	ret = copy_to_user((void __user *)(uintptr_t)params.hdr_uaddr, hdr,
+				params.hdr_len);
+
+e_free:
+	kfree(data);
+e_free_trans_data:
+	kfree(trans_data);
+e_free_hdr:
+	kfree(hdr);
+e_unpin:
+	sev_unpin_memory(kvm, guest_page, n);
+
+	return ret;
+}
+
 static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
 {
 	struct kvm_sev_cmd sev_cmd;
@@ -7321,6 +7446,9 @@  static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
 	case KVM_SEV_SEND_START:
 		r = sev_send_start(kvm, &sev_cmd);
 		break;
+	case KVM_SEV_SEND_UPDATE_DATA:
+		r = sev_send_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 17bef4c245e1..d9dc81bb9c55 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1570,6 +1570,15 @@  struct kvm_sev_send_start {
 	__u32 session_len;
 };
 
+struct kvm_sev_send_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)