[PATCH v8 0/5] Add TDX Guest Attestation support

Kuppuswamy Sathyanarayanan
2022-06-09T02:53:01Z

Hi All,

Intel's Trust Domain Extensions (TDX) protect guest VMs from malicious
hosts and some physical attacks. VM guest with TDX support is called
as TD Guest.

In TD Guest, the attestation process is used to verify the
trustworthiness of TD guest to the 3rd party servers. Such attestation
process is required by 3rd party servers before sending sensitive
information to TD guests. One usage example is to get encryption keys
from the key server for mounting the encrypted rootfs or secondary drive.

Following patches add the attestation support to TDX guest which
includes attestation user interface driver and related hypercall support.

Any distribution enabling TDX is also expected to need attestation. So
enable it by default with TDX guest support. The compiled size is
quite small (~500 bytes).

Changes since v7:
* Removed exports symbols for tdx_setup_ev_notify_handler() and
tdx_remove_ev_notify_handler().
* Changed "struct quote_buf *buf" member in "struct quote_entry"
from pointer to embed object.
* Rebased on top of v5.19-rc1.

Changes since v6:
* Fixed race between wait_for_completion_*() and
quote_callback_handler() in tdx_get_quote() when user terminates the
request.
* Fixed commit log and comments.

Changes since v5:
* Added support for parallel GetQuote requests.
* Add noalias variants of set_memory_*crypted() functions to
changes page attribute without touching direct map.
* Made set_memory_*crypted() functions vmalloc address compatible.
* Use vmap()/set_memory_*crypted() functions to share/unshare
memory without touching the direct map.
* Add support to let driver handle the memory cleanup for the
early termination of user requests.
* Removed unused headers in attest.c
* Fixed commit log and comments as per review comments.

Changes since v4:
* Removed platform driver model in attestation driver and used
miscdevice and initcall approach.
* Since dma_alloc*() APIs require a valid device reference,
replaced it with __get_free_pages() and set_memory_decrypted()
for quote memory allocation.
* Removed tdx_mcall_tdreport() and moved TDG.MR.REPORT TDCALL code
to tdx_get_report().
* Used kmalloc() for TDREPORT memory allocation instead of
get_zeroed_page().
* Returned -EINVAL in default case of tdx_attest_ioctl().
* Added struct tdx_report_req to explicitly mention the
TDX_CMD_GET_REPORT IOCTL argument.
* Removed tdx_get_quote_hypercall() and moved hypercall code to
attestation driver itself.
* Removed GetQuote timeout support (since it is not defined in
spec)
* Added support to check for spurious callback interrupt in GetQuote
request.
* Fixed commit log and comments as per review suggestions.

Changes since v3:
* Moved the attestation driver from platform/x86 to arch/x86/coco/tdx/ and
renamed intel_tdx_attest.c to attest.c.
* Dropped CONFIG_INTEL_TDX_ATTESTATION and added support to compile
attestation changes with CONFIG_INTEL_TDX_GUEST option.
* Merged patch titled "x86/tdx: Add tdx_mcall_tdreport() API support" and
"platform/x86: intel_tdx_attest: Add TDX Guest attestation interface" into
a single patch.
* Moved GetQuote IOCTL support changes from patch titled "platform/x86:
intel_tdx_attest: Add TDX Guest attestation interface driver" to a
separate patch.
* Removed 8K size restriction when requesting quote, and added support
to let userspace decide the quote size.
* Added support to allow attestation agent configure quote generation
timeout value.
* Fixed commit log and comments as per review comments.

Changes since v2:
* As per Han's suggestion, modified the attestation driver to use
platform device driver model.
* Modified tdx_hcall_get_quote() and tdx_mcall_tdreport() APIs to
return TDCALL error code instead of generic error info (like -EIO).
* Removed attestation test app patch from this series to simplify
the patchset and review process. Test app patches will be submitted
once attestation support patches are merged.
* Since patches titled "x86/tdx: Add SetupEventNotifyInterrupt TDX
hypercall support" and "x86/tdx: Add TDX Guest event notify
interrupt vector support" are related, combining them into a
single patch.

Changes since v1:
* Moved test driver from "tools/tdx/attest/tdx-attest-test.c" to
"tools/arch/x86/tdx/attest/tdx-attest-test.c" as per Hans review
suggestion.
* Minor commit log and comment fixes in patches titled
"x86/tdx: Add tdx_mcall_tdreport() API support" and "x86/tdx:
Add tdx_hcall_get_quote() API support"
* Extended tdx_hcall_get_quote() API to accept GPA length as argument
to accomodate latest TDQUOTE TDVMCALL related specification update.
* Added support for tdx_setup_ev_notify_handler() and
tdx_remove_ev_notify_handler() in patch titled "x86/tdx: Add TDX
Guest event notify interrupt vector support"

Kuppuswamy Sathyanarayanan (5):
x86/tdx: Add TDX Guest attestation interface driver
x86/tdx: Add TDX Guest event notify interrupt support
x86/mm: Make tdx_enc_status_changed() vmalloc address compatible
x86/mm: Add noalias variants of set_memory_*crypted() functions
x86/tdx: Add Quote generation support

arch/x86/coco/tdx/Makefile | 2 +-
arch/x86/coco/tdx/attest.c | 422 +++++++++++++++++++++++++++++
arch/x86/coco/tdx/tdx.c | 82 +++++-
arch/x86/include/asm/hardirq.h | 3 +
arch/x86/include/asm/idtentry.h | 4 +
arch/x86/include/asm/irq_vectors.h | 7 +-
arch/x86/include/asm/set_memory.h | 2 +
arch/x86/include/asm/tdx.h | 4 +
arch/x86/include/uapi/asm/tdx.h | 87 ++++++
arch/x86/kernel/irq.c | 7 +
arch/x86/mm/pat/set_memory.c | 26 +-
11 files changed, 636 insertions(+), 10 deletions(-)
create mode 100644 arch/x86/coco/tdx/attest.c
create mode 100644 arch/x86/include/uapi/asm/tdx.h

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2.25.1