From: Hans de Goede <hdegoede@redhat.com>
To: Sathyanarayanan Kuppuswamy
<sathyanarayanan.kuppuswamy@linux.intel.com>,
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, Mark Gross <mgross@linux.intel.com>
Cc: "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>,
linux-kernel@vger.kernel.org,
platform-driver-x86@vger.kernel.org
Subject: Re: [PATCH v2 5/6] platform/x86: intel_tdx_attest: Add TDX Guest attestation interface driver
Date: Mon, 11 Apr 2022 16:38:33 +0200 [thread overview]
Message-ID: <47d06f45-c1b5-2c8f-d937-3abacbf10321@redhat.com> (raw)
In-Reply-To: <aece84e1-2c90-2c18-993a-96f8fed7bb46@linux.intel.com>
Hi,
On 4/4/22 21:56, Sathyanarayanan Kuppuswamy wrote:
> Hi Hans,
>
> On 4/4/22 3:07 AM, Hans de Goede wrote:
>>> +static int __init tdx_attest_init(void)
>>> +{
>>> + dma_addr_t handle;
>>> + long ret = 0;
>>> +
>>> + mutex_lock(&attestation_lock);
>>> +
>>> + ret = misc_register(&tdx_attest_device);
>>> + if (ret) {
>>> + pr_err("misc device registration failed\n");
>>> + mutex_unlock(&attestation_lock);
>>> + return ret;
>>> + }
>> Why not do this as the last thing of the probe?
>
> We need misc device reference in dma_alloc_coherent() and
> dma_set_coherent_mask() calls. This is the reason for keeping
> misc_register() at the beginining of the init function.
Erm, you are supposed to pass an actual device-device as
parameter to dma_alloc_coherent(), so that it can see
what bus/dma-domain the device is connected to and if
an ioMMU might be involved...
>> That will avoid the need to unregister this again in all
>> the error-exit paths and also fixes a possible deadlock.
>>
>
> Agree. But, unless we create another device locally, I don't
> think we can avoid this. Do you prefer this approach?
Yes, passing the "struct device" which is embedded inside
a miscdevice as device to dma_alloc_coherent() is just
wrong. Please make your module_init function register
a platform_device using platform_device_register_simple()
(on systems with TDX support) and then turn your code/driver
into a standard platform_driver using the platform_device
which the driver binds to as parameter to dma_alloc_coherent().
See: https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/commit/?id=c4d2ff35d350428eca2ae1a1e2119e4c6297811d
for a simple (completely unrelated) driver which uses this
method to have a device to bind to for talking to a secondary
function of the embedded-controller on some platforms.
Regards,
Hans
next prev parent reply other threads:[~2022-04-11 14:38 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-30 22:17 [PATCH v2 0/6] Add TDX Guest Attestation support Kuppuswamy Sathyanarayanan
2022-03-30 22:18 ` [PATCH v2 1/6] x86/tdx: Add tdx_mcall_tdreport() API support Kuppuswamy Sathyanarayanan
2022-03-30 22:18 ` [PATCH v2 2/6] x86/tdx: Add tdx_hcall_get_quote() " Kuppuswamy Sathyanarayanan
2022-03-31 1:55 ` Aubrey Li
2022-03-30 22:18 ` [PATCH v2 3/6] x86/tdx: Add SetupEventNotifyInterrupt TDX hypercall support Kuppuswamy Sathyanarayanan
2022-03-30 22:18 ` [PATCH v2 4/6] x86/tdx: Add TDX Guest event notify interrupt vector support Kuppuswamy Sathyanarayanan
2022-03-30 22:18 ` [PATCH v2 5/6] platform/x86: intel_tdx_attest: Add TDX Guest attestation interface driver Kuppuswamy Sathyanarayanan
2022-04-04 10:07 ` Hans de Goede
2022-04-04 19:56 ` Sathyanarayanan Kuppuswamy
2022-04-11 14:38 ` Hans de Goede [this message]
2022-04-04 10:09 ` Hans de Goede
2022-04-04 10:11 ` Hans de Goede
2022-03-30 22:18 ` [PATCH v2 6/6] tools/tdx: Add a sample attestation user app Kuppuswamy Sathyanarayanan
-- strict thread matches above, loose matches on Subject: below --
2021-07-07 20:42 [PATCH v2 0/6] Add TDX Guest Support (Attestation support) Kuppuswamy Sathyanarayanan
2021-07-07 20:42 ` [PATCH v2 5/6] platform/x86: intel_tdx_attest: Add TDX Guest attestation interface driver Kuppuswamy Sathyanarayanan
2021-07-08 22:21 ` Andy Lutomirski
2021-07-08 22:35 ` Dave Hansen
2021-07-09 0:38 ` Andi Kleen
2021-07-13 0:33 ` Kuppuswamy, Sathyanarayanan
2021-07-13 0:44 ` Dave Hansen
2021-07-08 23:34 ` Kuppuswamy, Sathyanarayanan
2021-07-08 23:36 ` Dan Williams
2021-07-08 23:57 ` Kuppuswamy, Sathyanarayanan
2021-07-09 0:20 ` Dan Williams
2021-07-09 0:36 ` Andi Kleen
2021-07-09 1:37 ` Dan Williams
2021-07-09 1:44 ` Andi Kleen
2021-07-09 2:04 ` Dan Williams
2021-07-09 2:43 ` Kuppuswamy, Sathyanarayanan
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