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Re: [Qemu-devel] [PATCH 1/2] docs/specs: initial spec summary for Ultrav
From: |
David Gibson |
Subject: |
Re: [Qemu-devel] [PATCH 1/2] docs/specs: initial spec summary for Ultravisor-related hcalls |
Date: |
Fri, 12 Jul 2019 16:40:27 +1000 |
User-agent: |
Mutt/1.12.0 (2019-05-25) |
On Thu, Jul 11, 2019 at 08:19:33PM -0500, Michael Roth wrote:
> For now this only covers hcalls relating to TPM communication since
> it's the only one particularly important from a QEMU perspective atm,
> but others can be added here where it makes sense.
>
> The full specification for all hcalls/ucalls will eventually be made
> available in the public/OpenPower version of the PAPR specification.
>
> Signed-off-by: Michael Roth <address@hidden>
Thanks for adding this documentation. Is there a PAPR extension
proposal which covers this, which we could cite as the source?
> ---
> docs/specs/ppc-spapr-uv-hcalls.txt | 74 ++++++++++++++++++++++++++++++
> 1 file changed, 74 insertions(+)
> create mode 100644 docs/specs/ppc-spapr-uv-hcalls.txt
>
> diff --git a/docs/specs/ppc-spapr-uv-hcalls.txt
> b/docs/specs/ppc-spapr-uv-hcalls.txt
> new file mode 100644
> index 0000000000..0278f89190
> --- /dev/null
> +++ b/docs/specs/ppc-spapr-uv-hcalls.txt
> @@ -0,0 +1,74 @@
> +On PPC64 systems supporting Protected Execution Facility (PEF), system
> +memory can be placed in a secured region where only an "ultravisor"
> +running in firmware can provide to access it. pseries guests on such
> +systems can communicate with the ultravisor (via ultracalls) to switch to a
> +secure VM mode (SVM) where the guest's memory is relocated to this secured
> +region, making its memory inaccessible to normal processes/guests running on
> +the host.
> +
> +The various ultracalls/hypercalls relating to SVM mode are currently
> +only documented internally, but are planned for direct inclusion into the
> +public OpenPOWER version of the PAPR specification (LoPAPR/LoPAR). An
> internal
> +ACR has been filed to reserve a hypercall number range specific to this
> +use-case to avoid any future conflicts with the internally-maintained PAPR
> +specification. This document summarizes some of these details as they relate
> +to QEMU.
> +
> +== hypercalls needed by the ultravisor ==
> +
> +Switching to SVM mode involves a number of hcalls issued by the ultravisor
> +to the hypervisor to orchestrate the movement of guest memory to secure
> +memory and various other aspects SVM mode. The below documents the hcalls
> +relevant to QEMU.
> +
> +- H_TPM_COMM (0xef10)
> +
> + For TPM_COMM_OP_EXECUTE operation:
> + Send a request to a TPM and receive a response, opening a new TPM session
> + if one has not already been opened.
> +
> + For TPM_COMM_OP_CLOSE_SESSION operation:
> + Close the existing TPM session, if any.
> +
> + Arguments:
> +
> + r3 : H_TPM_COMM (0xef10)
> + r4 : TPM operation, one of:
> + TPM_COMM_OP_EXECUTE (0x1)
> + TPM_COMM_OP_CLOSE_SESSION (0x2)
> + r5 : in_buffer, guest physical address of buffer containing the request
> + - Caller may use the same address for both request and response
> + r6 : in_size, size of the in buffer, must
> + - Must be less than or equal to 4KB
> + r7 : out_buffer, guest physical address of buffer to store the response
> + - Caller may use the same address for both request and response
> + r8 : out_size, size of the out buffer
> + - Must be at least 4KB, as this is the maximum request/response size
> + supported by most TPM implementations, including the TPM Resource
> + Manager in the linux kernel.
> +
> + Return values:
> +
> + r3 : H_Success request processed successfully
> + H_PARAMETER invalid TPM operation
> + H_P2 in_buffer is invalid
> + H_P3 in_size is invalid
> + H_P4 out_buffer is invalid
> + H_P5 out_size is invalid
> + H_RESOURCE TPM is unavailable
> + r4 : For TPM_COMM_OP_EXECUTE, the size of the response will be stored
> here
> + upon success.
> +
> + Use-case/notes:
> +
> + SVM filesystems are encrypted using a symmetric key. This key is then
> + wrapped/encrypted using the public key of a trusted system which has the
> + private key stored in the system's TPM. An Ultravisor will use this
> + hcall to unwrap/unseal the symmetric key using the system's TPM device
> + or a TPM Resource Manager associated with the device.
> +
> + The Ultravisor sets up a separate session key with the TPM in advance
> + during host system boot. All sensitive in and out values will be
> + encrypted using the session key. Though the hypervisor will see the 'in'
> + and 'out' buffers in raw form, any sensitive contents will generally be
> + encrypted using this session key.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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[Qemu-devel] [PATCH 2/2] spapr: initial implementation for H_TPM_COMM hcall, Michael Roth, 2019/07/11
- Re: [Qemu-devel] [PATCH 2/2] spapr: initial implementation for H_TPM_COMM hcall, David Gibson, 2019/07/12
- Re: [Qemu-devel] [PATCH 2/2] spapr: initial implementation for H_TPM_COMM hcall, Michael Roth, 2019/07/12
- Re: [Qemu-devel] [PATCH 2/2] spapr: initial implementation for H_TPM_COMM hcall, David Gibson, 2019/07/15
- Re: [Qemu-devel] [PATCH 2/2] spapr: initial implementation for H_TPM_COMM hcall, Michael Roth, 2019/07/16
- Re: [Qemu-devel] [PATCH 2/2] spapr: initial implementation for H_TPM_COMM hcall, David Gibson, 2019/07/16
- Re: [Qemu-devel] [PATCH 2/2] spapr: initial implementation for H_TPM_COMM hcall, Michael Roth, 2019/07/17