linux-kernel - Re: [PATCH] KVM: x86/xen: fix 32-bit pointer cast

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Date: Thu, 22 Feb 2024 07:04:44 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: paul@....org
Cc: Arnd Bergmann <arnd@...nel.org>, David Woodhouse <dwmw2@...radead.org>, 
	Paolo Bonzini <pbonzini@...hat.com>, Arnd Bergmann <arnd@...db.de>, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>, Jens Axboe <axboe@...nel.dk>, Jan Kara <jack@...e.cz>, 
	Christian Brauner <brauner@...nel.org>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: x86/xen: fix 32-bit pointer cast

On Thu, Feb 22, 2024, Paul Durrant wrote:
> On 22/02/2024 10:03, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@...db.de>
> > 
> > shared_info.hva is a 64-bit variable, so casting to a pointer causes
> > a warning in 32-bit builds:
> > 
> > arch/x86/kvm/xen.c: In function 'kvm_xen_hvm_set_attr':
> > arch/x86/kvm/xen.c:660:45: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
> >    660 |                         void __user * hva = (void *)data->u.shared_info.hva;
> > 
> > Replace the cast with a u64_to_user_ptr() call that does the right thing.
> 
> Thanks Arnd. I'd just got a ping from kernel test robot for lack of __user
> qualifier in the cast
> (https://lore.kernel.org/oe-kbuild-all/202402221721.mhF8MNVh-lkp@intel.com/),
> which this should also fix.

Ya, 'tis a good bot.  I squashed this in.   Paul/David, new hashes for the
affected commits are below.

Thanks Arnd!

  KVM: x86/xen: allow shared_info to be mapped by fixed HVA
  https://github.com/kvm-x86/linux/commit/b9220d32799a
  KVM: x86/xen: allow vcpu_info to be mapped by fixed HVA
  https://github.com/kvm-x86/linux/commit/3991f35805d0
  KVM: selftests: map Xen's shared_info page using HVA rather than GFN
  https://github.com/kvm-x86/linux/commit/9397b5334af1
  KVM: selftests: re-map Xen's vcpu_info using HVA rather than GPA
  https://github.com/kvm-x86/linux/commit/b4dfbfdc9538
  KVM: x86/xen: advertize the KVM_XEN_HVM_CONFIG_SHARED_INFO_HVA capability
  https://github.com/kvm-x86/linux/commit/615451d8cb3f
  KVM: pfncache: check the need for invalidation under read lock first
  https://github.com/kvm-x86/linux/commit/9fa336e343b2
  KVM: x86/xen: allow vcpu_info content to be 'safely' copied
  https://github.com/kvm-x86/linux/commit/003d914220c9