linux-kernel - Re: [PATCH 5/5][RFC] selftests/pfru: add test for Platform Firmware Runtime Update and Telemetry

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Date:   Tue, 14 Sep 2021 14:46:49 +0800
From:   Chen Yu <yu.c.chen@...el.com>
To:     Shuah Khan <skhan@...uxfoundation.org>
Cc:     linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <len.brown@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Andy Shevchenko <andriy.shevchenko@...el.com>,
        Aubrey Li <aubrey.li@...el.com>,
        Ashok Raj <ashok.raj@...el.com>, Shuah Khan <shuah@...nel.org>,
        linux-kselftest@...r.kernel.org,
        Dou Shengnan <shengnanx.dou@...el.com>
Subject: Re: [PATCH 5/5][RFC] selftests/pfru: add test for Platform Firmware
 Runtime Update and Telemetry

Hi Shuah, thank you for taking a look at this,
On Tue, Sep 07, 2021 at 03:28:52PM -0600, Shuah Khan wrote:
> On 9/7/21 9:40 AM, Chen Yu wrote:
> > Introduce a simple test for Platform Firmware Runtime Update and Telemetry
> > drivers. It is based on ioctl to either update firmware driver or code injection,
> > and read corresponding PFRU Telemetry log into user space.
> > 
> 
> A few things to consider and add handling for them in the
> test.
> 
> What happens when non-root user runs this test?
Currently the code does not distinguish between root and non-root. The
next version will terminate if the user is non-root.
> What happens when the pfru device doesn't exist?
> 
Currently the code terminates if either pfru_update or pfru_telemetry
device was not found.
> 
> [snip]
> 
> > +}
> > +
> > +int main(int argc, char *argv[])
> > +{
> > +	int fd_update, fd_log, fd_capsule;
> > +	struct telem_data_info data_info;
> > +	struct telem_info info;
> > +	struct update_cap_info cap;
> > +	void *addr_map_capsule;
> > +	struct stat st;
> > +	char *log_buf;
> > +	int ret = 0;
> > +
> > +	parse_options(argc, argv);
> > +
> > +	fd_log = open("/dev/pfru/telemetry", O_RDWR);
> > +	if (fd_log < 0) {
> > +		perror("Cannot open telemetry device...");
> > +		return 1;
> > +	}
> 
> Is this considered an error or unsupported?
> 
> > +	fd_update = open("/dev/pfru/update", O_RDWR);
> > +	if (fd_update < 0) {
> > +		perror("Cannot open code injection device...");
> > +		return 1;
> > +	}
> > +
> 
> Same here. If test is run on platform with pfru test should skip
> instead of reporting failure/error.
> 
Okay, got it. The next version will do the following to fix this:
1. If the pfru_update device is not found, the test will terminate.
   This is because the pfru_update driver is the fundamental driver.
   If this driver is not detected, there would be no information at all.
2. If the pfru_telemetry device is not found, the test will skip
   the log setting/retrieving. Since the pfru_telemetry driver
   is optional, the user can still update the firmware without
   checking the telemetry log.

Thanks,
Chenyu