Re: Re: [PATCH 6.18 091/270] LoongArch: KVM: Compile switch.S directly into the kernel

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, May 13, 2026 at 07:58:10PM +0800, Wentao Guan wrote:
> Hello,
> 
> > On Wed, May 13, 2026 at 11:06:20AM +0800, Huacai Chen wrote:
> > > On Wed, May 13, 2026 at 5:53 AM Sean Christopherson <seanjc@google.com> wrote:
> > > >
> > > > On Tue, May 12, 2026, Miguel Ojeda wrote:
> > > > > On Tue, 12 May 2026 19:38:12 +0200 Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> > > > > >
> > > > > > 6.18-stable review patch.  If anyone has any objections, please let me know.
> > > > > >
> > > > > > ------------------
> > > > > >
> > > > > > From: Xianglai Li <lixianglai@loongson.cn>
> > > > > >
> > > > > > commit 5203012fa6045aac4b69d4e7c212e16dcf38ef10 upstream.
> > > > > >
> > > > > > If we directly compile the switch.S file into the kernel, the address of
> > > > > > the kvm_exc_entry function will definitely be within the DMW memory area.
> > > > > > Therefore, we will no longer need to perform a copy relocation of the
> > > > > > kvm_exc_entry.
> > > > > >
> > > > > > So this patch compiles switch.S directly into the kernel, and then remove
> > > > > > the copy relocation execution logic for the kvm_exc_entry function.
> > > > > >
> > > > > > Cc: stable@vger.kernel.org
> > > > > > Signed-off-by: Xianglai Li <lixianglai@loongson.cn>
> > > > > > Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
> > > > > > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > > > >
> > > > > For loongarch64, I am seeing a bunch of errors like:
> > > > >
> > > > >     arch/loongarch/kvm/switch.S:201:1: error: unrecognized instruction mnemonic
> > > > >     EXPORT_SYMBOL_FOR_KVM(kvm_exc_entry)
> > > > >     ^
> > > > >
> > > > > `EXPORT_SYMBOL_FOR_KVM` does not exist in 6.18. Does this need a subset
> > > > > of commit 6276c67f2bc4 ("x86: Restrict KVM-induced symbol exports to KVM
> > > > > modules where obvious/possible")?
> > > >
> > > > Either that or just convert EXPORT_SYMBOL_FOR_KVM() => EXPORT_SYMBOL_GPL().  If
> > > > that's somewhat scriptable for ongoing LTS backports, that's probably the best
> > > > option.  EXPORT_SYMBOL_FOR_KVM() will only work for 6.18, and the list of backports
> > > > needed to get EXPORT_SYMBOL_FOR_MODULES() working on older LTS kernels looks to
> > > > be non-trivial
> > > >
> > > > If we do end up backporting EXPORT_SYMBOL_FOR_KVM() and others, we might as well
> > > > also grab a subset of 01122b89361e ("perf: Use EXPORT_SYMBOL_FOR_KVM() for the
> > > > mediated APIs") to ensure a kvm_types.h stub is present on all archs.  That way
> > > > EXPORT_SYMBOL_FOR_KVM() usage in arch-neutral code will also work.
> > > I have already noticed Greg about this before.
> > 
> > You did?  Where?
> 
> Small problem, I guess where he means is 'stable-commits@vger.kernel.org', is a
> not public maillist? I want to find it in 'lore.kernel.org' but not found... 

It's a public list, anyone can sign up for it.  Don't know if lore
archives it, but I'm sure that someone does...

thanks,

greg k-h