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

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On 22/02/2024 10:03, Arnd Bergmann wrote:
From: Arnd Bergmann <arnd@xxxxxxxx>

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@xxxxxxxxx/), which this should also fix.


Fixes: 01a871852b11 ("KVM: x86/xen: allow shared_info to be mapped by fixed HVA")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
  arch/x86/kvm/xen.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)


Reviewed-by: Paul Durrant <paul@xxxxxxx>

diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index 01c0fd138d2f..8a04e0ae9245 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -657,7 +657,7 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
  						     gfn_to_gpa(gfn), PAGE_SIZE);
  			}
  		} else {
-			void __user * hva = (void *)data->u.shared_info.hva;
+			void __user * hva = u64_to_user_ptr(data->u.shared_info.hva);
if (!PAGE_ALIGNED(hva) || !access_ok(hva, PAGE_SIZE)) {
  				r = -EINVAL;





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