On 1/24/19 1:00 PM, Andrew Jones wrote:
> On Thu, Jan 24, 2019 at 11:16:32AM +0000, Alexandru Elisei wrote:
>> On arm and arm64, kvm-unit-tests uses the QEMU chr-testdev device to shut
>> down the virtual machine at the end of a test. The function
>> psci_system_off() provides another mechanism for terminating the virtual
>> machine. If the chr-testdev device hasn't been initialized successfully,
>> then use psci_system_off() to terminate the test instead of
>> chr_testdev_exit().
>>
>> chr-testdev is implemented on top of virtio console. This patch makes it
>> possible for a virtual machine manager which doesn't have support for
>> chr-testdev, but has been configured not to emulate a virtio console, to
>> gracefully terminate a virtual machine after a test has been completed.
>>
>> There is one limitation to using psci_system_off() to terminate a test:
>> chr-testdev allows kvm-unit-tests to specify an exit code;
>> psci_system_off() has no such mechanism.
>>
>> Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
>> ---
>> lib/arm/io.c | 14 ++++++++++++--
>> 1 file changed, 12 insertions(+), 2 deletions(-)
>>
>> diff --git a/lib/arm/io.c b/lib/arm/io.c
>> index 87435150f73e..9fe9bd0bf659 100644
>> --- a/lib/arm/io.c
>> +++ b/lib/arm/io.c
>> @@ -11,6 +11,7 @@
>> #include <libcflat.h>
>> #include <devicetree.h>
>> #include <chr-testdev.h>
>> +#include "arm/asm/psci.h"
>> #include <asm/spinlock.h>
>> #include <asm/io.h>
>>
>> @@ -18,6 +19,8 @@
>>
>> extern void halt(int code);
>>
>> +static bool testdev_enabled;
>> +
>> /*
>> * Use this guess for the pl011 base in order to make an attempt at
>> * having earlier printf support. We'll overwrite it with the real
>> @@ -65,8 +68,12 @@ static void uart0_init(void)
>>
>> void io_init(void)
>> {
>> + int err;
>> +
>> uart0_init();
>> - chr_testdev_init();
>> + err = chr_testdev_init();
>> + if (!err)
>> + testdev_enabled = true;
>> }
>>
>> void puts(const char *s)
>> @@ -79,7 +86,10 @@ void puts(const char *s)
>>
>> void exit(int code)
>> {
>> - chr_testdev_exit(code);
>> + if (testdev_enabled)
>> + chr_testdev_exit(code);
>> + else
>> + psci_system_off();
>> halt(code);
>> __builtin_unreachable();
>> }
>> --
>> 2.17.0
>>
> chr_testdev_init() ensures vcon is NULL if it fails to initialize.
> chr_testdev_exit() immediately returns if vcon is NULL. This was
> done by design to allow fallback exits to be placed below the
> chr_testdev_exit call, e.g. halt().
>
> We should be able to drop patch 3/7 and change exit() to this
>
> void exit(int code)
> {
> chr_testdev_exit(code);
> psci_system_off();
> halt(code);
> __builtin_unreachable();
> }
>
> Thanks,
> drew
I wasn't aware of this design decision, thank you for explaining it. I'll
implement the changes you suggested, including dropping patch 3/7: "lib:
chr-testdev: Make chr_testdev_init() return status".
