On Fri, Oct 06, 2023, Jakub Kicinski wrote: > Setting WERROR for random subsystems make life really hard > for subsystems which want to build-test their stuff with W=1. > WERROR for the entire kernel now exists and can be used > instead. W=1 people probably know how to deal with the global > W=1 already, tracking all per-subsystem WERRORs is too much... I assume s/W=1/WERROR=y in this line? > Link: https://lore.kernel.org/all/0da9874b6e9fcbaaa5edeb345d7e2a7c859fc818.1696271334.git.thomas.lendacky@xxxxxxx/ > Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> > --- > Documentation/process/maintainer-kvm-x86.rst | 2 +- > arch/x86/kvm/Kconfig | 14 -------------- > arch/x86/kvm/Makefile | 1 - > 3 files changed, 1 insertion(+), 16 deletions(-) > > diff --git a/Documentation/process/maintainer-kvm-x86.rst b/Documentation/process/maintainer-kvm-x86.rst > index 9183bd449762..cd70c0351108 100644 > --- a/Documentation/process/maintainer-kvm-x86.rst > +++ b/Documentation/process/maintainer-kvm-x86.rst > @@ -243,7 +243,7 @@ context and disambiguate the reference. > Testing > ------- > At a bare minimum, *all* patches in a series must build cleanly for KVM_INTEL=m > -KVM_AMD=m, and KVM_WERROR=y. Building every possible combination of Kconfigs > +KVM_AMD=m, and WERROR=y. Building every possible combination of Kconfigs > isn't feasible, but the more the merrier. KVM_SMM, KVM_XEN, PROVE_LOCKING, and > X86_64 are particularly interesting knobs to turn. > > diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig > index ed90f148140d..12929324ac3e 100644 > --- a/arch/x86/kvm/Kconfig > +++ b/arch/x86/kvm/Kconfig > @@ -63,20 +63,6 @@ config KVM > > If unsure, say N. > > -config KVM_WERROR > - bool "Compile KVM with -Werror" > - # KASAN may cause the build to fail due to larger frames > - default y if X86_64 && !KASAN Hrm, I am loath to give up KVM's targeted -Werror as it allows for more aggresive enabling, e.g. enabling CONFIG_WERROR for i386 builds with other defaults doesn't work because of CONFIG_FRAME_WARN=1024. That in turns means making WERROR=y a requirement in maintainer-kvm-x86.rst is likely unreasonable. And arguably KVM_WERROR is doing its job by flagging the linked W=1 error. The problem there lies more in my build testing, which I'll go fix by adding a W=1 configuration or three. As the changelog notes, I highly doubt W=1 builds work with WERROR, whereas keeping KVM x86 warning-free even with W=1 is feasible. > - # We use the dependency on !COMPILE_TEST to not be enabled > - # blindly in allmodconfig or allyesconfig configurations > - depends on KVM > - depends on (X86_64 && !KASAN) || !COMPILE_TEST On a related topic, this is comically stale as WERROR is on by default for both allmodconfig and allyesconfig, which work because they trigger 64-bit builds. And KASAN on x86 is 64-bit only. Rather than yank out KVM_WERROR entirely, what if we make default=n and trim the depends down to "KVM && EXPERT && !KASAN"? E.g. diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig index 8452ed0228cb..c2466304aa6a 100644 --- a/arch/x86/kvm/Kconfig +++ b/arch/x86/kvm/Kconfig @@ -65,13 +65,12 @@ config KVM config KVM_WERROR bool "Compile KVM with -Werror" - # KASAN may cause the build to fail due to larger frames - default y if X86_64 && !KASAN - # We use the dependency on !COMPILE_TEST to not be enabled - # blindly in allmodconfig or allyesconfig configurations - depends on KVM - depends on (X86_64 && !KASAN) || !COMPILE_TEST - depends on EXPERT + # Disallow KVM's -Werror if KASAN=y, e.g. to guard against randomized + # configs from selecting KVM_WERROR=y. KASAN builds generates warnings + # for the default FRAME_WARN, i.e. KVM_WERROR=y with KASAN=y requires + # special tuning. Building KVM with -Werror and KASAN is still doable + * via enabling the kernel-wide WERROR=y. + depends on KVM && EXPERT && !KASAN help Add -Werror to the build flags for KVM.
