From: Kai Huang <kai.huang@intel.com>
To: Sathyanarayanan Kuppuswamy
<sathyanarayanan.kuppuswamy@linux.intel.com>,
Dave Hansen <dave.hansen@intel.com>,
"Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Tony Luck <tony.luck@intel.com>, Andi Kleen <ak@linux.intel.com>,
Wander Lairson Costa <wander@redhat.com>,
Isaku Yamahata <isaku.yamahata@gmail.com>,
marcelo.cerri@canonical.com, tim.gardner@canonical.com,
khalid.elmously@canonical.com, philip.cox@canonical.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 3/3] x86/tdx: Add Quote generation support
Date: Thu, 05 May 2022 22:50:09 +1200 [thread overview]
Message-ID: <1534b975275b78d61d851eb86faa226fd9be5c7a.camel@intel.com> (raw)
In-Reply-To: <40ccd0f0-35a1-5aa7-9e51-25ab196d79e5@linux.intel.com>
> + /* Submit GetQuote Request */
> + ret = tdx_get_quote_hypercall(buf);
> + if (ret) {
> + pr_err("GetQuote hypercall failed, status:%lx\n", ret);
> + ret = -EIO;
> + goto free_entry;
> + }
> +
> + /* Add current quote entry to quote_list */
> + add_quote_entry(entry);
> +
> + /* Wait for attestation completion */
> + ret = wait_for_completion_interruptible(&entry->compl);
> + if (ret < 0) {
> + ret = -EIO;
> + goto del_entry;
> + }
This is misuse of wait_for_completion_interruptible().
xxx_interruptible() essentially means this operation can be interrupted by
signal. Using xxx_interruptible() in driver IOCTL essentially means when it
returns due to signal, the IOCTL should return -EINTR to let userspace know that
your application received some signal needs handling, and this IOCTL isn't
finished and you should retry. So here we should return -EINTR (and cleanup all
staff has been done) when wait_for_completion_interruptible() returns -
ERESTARTSYS (in fact, it returns only -ERESTARTSYS or 0).
Since normally userspace application just ignore signals, and in this particular
case, asking userspace to retry just makes things more complicated to handle, I
think you can just use wait_for_completion_killable(), which only returns when
the application receives signal that it is going to be killed.
> +
> + /* Copy output data back to user buffer */
> + if (copy_to_user((void __user *)quote_req.buf, buf->vmaddr,
> quote_req.len))
> + ret = -EFAULT;
> +
> +del_entry:
> + del_quote_entry(entry);
> +free_entry:
> + free_quote_entry(entry);
As I (and Isaku) mentioned before, when wait_for_completion_killable() returns
with error, you cannot just convert the buffer to private and free it. The VMM
is still owning it (IN_FLIGHT).
One way to handle is you can put those buffers that are still owned by VMM to a
new list, and have some kernel thread to periodically check buffer's status and
free those are already released by VMM. I haven't thought thoroughly, so maybe
there's better way to handle, though.
--
Thanks,
-Kai
next prev parent reply other threads:[~2022-05-05 10:50 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-01 18:34 [PATCH v5 0/3] Add TDX Guest Attestation support Kuppuswamy Sathyanarayanan
2022-05-01 18:34 ` [PATCH v5 1/3] x86/tdx: Add TDX Guest attestation interface driver Kuppuswamy Sathyanarayanan
2022-05-02 2:31 ` Kai Huang
2022-05-02 15:52 ` Sathyanarayanan Kuppuswamy
2022-05-02 22:30 ` Kai Huang
2022-05-02 23:17 ` Sathyanarayanan Kuppuswamy
2022-05-02 23:37 ` Kai Huang
2022-05-03 14:38 ` Wander Costa
2022-05-03 15:09 ` Sathyanarayanan Kuppuswamy
2022-05-03 22:08 ` Kai Huang
2022-05-02 12:18 ` Wander Lairson Costa
2022-05-02 16:06 ` Sathyanarayanan Kuppuswamy
2022-05-01 18:34 ` [PATCH v5 2/3] x86/tdx: Add TDX Guest event notify interrupt support Kuppuswamy Sathyanarayanan
2022-05-02 12:44 ` Wander Lairson Costa
2022-05-01 18:35 ` [PATCH v5 3/3] x86/tdx: Add Quote generation support Kuppuswamy Sathyanarayanan
2022-05-02 2:40 ` Kai Huang
2022-05-03 1:27 ` Kirill A. Shutemov
2022-05-03 2:18 ` Kai Huang
2022-05-03 2:39 ` Sathyanarayanan Kuppuswamy
2022-05-03 22:13 ` Kai Huang
2022-05-03 2:45 ` Kirill A. Shutemov
2022-05-03 3:36 ` Kai Huang
2022-05-03 22:24 ` Dave Hansen
2022-05-03 22:28 ` Sathyanarayanan Kuppuswamy
2022-05-03 22:30 ` Sathyanarayanan Kuppuswamy
2022-05-04 22:49 ` Sathyanarayanan Kuppuswamy
2022-05-04 23:28 ` Kai Huang
2022-05-05 20:53 ` Sathyanarayanan Kuppuswamy
2022-05-05 22:15 ` Kai Huang
2022-05-05 22:38 ` Sathyanarayanan Kuppuswamy
2022-05-05 23:06 ` Dave Hansen
2022-05-06 0:11 ` Kai Huang
2022-05-06 1:55 ` Sathyanarayanan Kuppuswamy
2022-05-07 0:42 ` Kirill A. Shutemov
2022-05-09 3:37 ` Kai Huang
2022-05-09 12:09 ` Kirill A. Shutemov
2022-05-09 14:14 ` Dave Hansen
2022-05-09 15:35 ` Kirill A. Shutemov
2022-05-09 15:43 ` Sathyanarayanan Kuppuswamy
2022-05-09 23:54 ` Kai Huang
2022-05-10 0:17 ` Sathyanarayanan Kuppuswamy
2022-05-10 1:30 ` Kirill A. Shutemov
2022-05-10 1:40 ` Kai Huang
2022-05-10 10:42 ` Kai Huang
2022-05-16 17:39 ` Sathyanarayanan Kuppuswamy
2022-05-06 11:00 ` Kai Huang
2022-05-06 15:47 ` Dave Hansen
2022-05-07 1:00 ` Kirill A. Shutemov
2022-05-05 10:50 ` Kai Huang [this message]
2022-05-05 19:03 ` Sathyanarayanan Kuppuswamy
2022-05-05 22:25 ` Kai Huang
2022-05-02 5:01 ` Kai Huang
2022-05-02 16:02 ` Sathyanarayanan Kuppuswamy
2022-05-02 23:02 ` Kai Huang
2022-05-02 13:16 ` Wander Lairson Costa
2022-05-02 16:05 ` Sathyanarayanan Kuppuswamy
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