Re: git: 63bf943d4af1 - main - Hyper-V: vmbus: Add NULL check for vmbus_res

> On Nov 2, 2023, at 5:30 PM, Mateusz Guzik <mjguzik@gmail.com> wrote:
> 
> On 11/2/23, Zhenlei Huang <zlei@freebsd.org <mailto:zlei@freebsd.org>> wrote:
>> Sorry I committed too fast.
>> 
>> I should give credentials to Souradeep in the commit message.
>> 
>> Thank him for the analysis !
>> 
> 
> again this kind of change you can revert and recommit with proper
> authorship, as long as it happens fast

I'm really really sorry for that.
I realized that until the commit has been MFCed into stable/14 and releng/14.0 . 

> 
>>> On Nov 2, 2023, at 5:09 PM, Zhenlei Huang <zlei@FreeBSD.org> wrote:
>>> 
>>> The branch main has been updated by zlei:
>>> 
>>> URL:
>>> https://cgit.FreeBSD.org/src/commit/?id=63bf943d4af17799cef21e2bb78dd28003ce1ce5
>>> 
>>> commit 63bf943d4af17799cef21e2bb78dd28003ce1ce5
>>> Author:     Zhenlei Huang <zlei@FreeBSD.org>
>>> AuthorDate: 2023-11-02 09:07:11 +0000
>>> Commit:     Zhenlei Huang <zlei@FreeBSD.org>
>>> CommitDate: 2023-11-02 09:07:11 +0000
>>> 
>>>   Hyper-V: vmbus: Add NULL check for vmbus_res
>>> 
>>>   QEMU emulates Hyper-V [1] but lacks the emulation for vmbus_res, thus
>>> no
>>>   coherence information is available. Add NULL check for it and fallback
>>>   to no coherence. This will prevent FreeBSD guests from panic on QEMU
>>>   with the Hyper-V enlightenment hv-synic enabled.
>>> 
>>>   For real Hyper-V, both gen1 and gen2 have vmbus_res then they are not
>>>   affected by this change.
>>> 
>>>   1. https://www.qemu.org/docs/master/system/i386/hyperv.html
>>> 
>>>   PR:             274810
>>>   Reviewed by:    mhorne, emaste, delphij, whu
>>>   Diagnosed by:   mhorne
>>>   Fixes:          e7a9817b8d32 Hyper-V: vmbus: implementat
>>> bus_get_dma_tag in vmbus
>>>   Insta-MFC approved by:  re (delphij) for 14.0-RC4
>>>   Differential Revision:  https://reviews.freebsd.org/D42414
>>> ---
>>> sys/dev/hyperv/vmbus/vmbus.c | 10 ++++++----
>>> 1 file changed, 6 insertions(+), 4 deletions(-)
>>> 
>>> diff --git a/sys/dev/hyperv/vmbus/vmbus.c b/sys/dev/hyperv/vmbus/vmbus.c
>>> index ee412e643b4f..0ea401507b79 100644
>>> --- a/sys/dev/hyperv/vmbus/vmbus.c
>>> +++ b/sys/dev/hyperv/vmbus/vmbus.c
>>> @@ -1393,7 +1393,7 @@ vmbus_doattach(struct vmbus_softc *sc)
>>> 	int ret;
>>> 	device_t dev_res;
>>> 	ACPI_HANDLE handle;
>>> -	unsigned int coherent;
>>> +	unsigned int coherent = 0;
>>> 
>>> 	if (sc->vmbus_flags & VMBUS_FLAG_ATTACHED)
>>> 		return (0);
>>> @@ -1416,10 +1416,12 @@ vmbus_doattach(struct vmbus_softc *sc)
>>> 
>>> 	/* Coherency attribute */
>>> 	dev_res =  devclass_get_device(devclass_find("vmbus_res"), 0);
>>> -	handle = acpi_get_handle(dev_res);
>>> +	if (dev_res != NULL) {
>>> +		handle = acpi_get_handle(dev_res);
>>> 
>>> -	if (ACPI_FAILURE(acpi_GetInteger(handle, "_CCA", &coherent)))
>>> -		coherent = 0;
>>> +		if (ACPI_FAILURE(acpi_GetInteger(handle, "_CCA", &coherent)))
>>> +			coherent = 0;
>>> +	}
>>> 	if (bootverbose)
>>> 		device_printf(sc->vmbus_dev, "Bus is%s cache-coherent\n",
>>> 			coherent ? "" : " not");
>> 
>> 
>> 
>> 
> 
> 
> -- 
> Mateusz Guzik <mjguzik gmail.com <http://gmail.com/>>