Date: Thu, 2 Nov 2023 17:22:09 +0800 From: Zhenlei Huang <zlei@FreeBSD.org> To: "src-committers@freebsd.org" <src-committers@FreeBSD.org>, "dev-commits-src-all@freebsd.org" <dev-commits-src-all@FreeBSD.org>, "dev-commits-src-main@freebsd.org" <dev-commits-src-main@FreeBSD.org> Cc: Souradeep Chakrabarti <schakrabarti@microsoft.com> Subject: Re: git: 63bf943d4af1 - main - Hyper-V: vmbus: Add NULL check for vmbus_res Message-ID: <2E6A685B-A8E4-48A2-B21A-422AFBEA4440@FreeBSD.org> In-Reply-To: <202311020909.3A299SXQ075865@gitrepo.freebsd.org> References: <202311020909.3A299SXQ075865@gitrepo.freebsd.org>
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Sorry I committed too fast. I should give credentials to Souradeep in the commit message. Thank him for the analysis ! > On Nov 2, 2023, at 5:09 PM, Zhenlei Huang <zlei@FreeBSD.org> wrote: >=20 > The branch main has been updated by zlei: >=20 > URL: = https://cgit.FreeBSD.org/src/commit/?id=3D63bf943d4af17799cef21e2bb78dd280= 03ce1ce5 >=20 > 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 >=20 > Hyper-V: vmbus: Add NULL check for vmbus_res >=20 > 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. >=20 > For real Hyper-V, both gen1 and gen2 have vmbus_res then they are = not > affected by this change. >=20 > 1. https://www.qemu.org/docs/master/system/i386/hyperv.html >=20 > 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(-) >=20 > 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 =3D 0; >=20 > if (sc->vmbus_flags & VMBUS_FLAG_ATTACHED) > return (0); > @@ -1416,10 +1416,12 @@ vmbus_doattach(struct vmbus_softc *sc) >=20 > /* Coherency attribute */ > dev_res =3D devclass_get_device(devclass_find("vmbus_res"), 0); > - handle =3D acpi_get_handle(dev_res); > + if (dev_res !=3D NULL) { > + handle =3D acpi_get_handle(dev_res); >=20 > - if (ACPI_FAILURE(acpi_GetInteger(handle, "_CCA", &coherent))) > - coherent =3D 0; > + if (ACPI_FAILURE(acpi_GetInteger(handle, "_CCA", = &coherent))) > + coherent =3D 0; > + } > if (bootverbose) > device_printf(sc->vmbus_dev, "Bus is%s = cache-coherent\n", > coherent ? "" : " not");
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