KVM: x86: hyper-v: fix type of valid_bank_mask

In kvm_hv_flush_tlb(), valid_bank_mask is declared as unsigned long,
but is used as u64, which is wrong for i386, and has been spotted by
LKP after applying "KVM: x86: hyper-v: replace bitmap_weight() with
hweight64()"

https://lore.kernel.org/lkml/20220510154750.212913-12-yury.norov@gmail.com/

But it's wrong even without that patch because now bitmap_weight()
dereferences a word after valid_bank_mask on i386.

>> include/asm-generic/bitops/const_hweight.h:21:76: warning: right shift count >= width of type
+[-Wshift-count-overflow]
      21 | #define __const_hweight64(w) (__const_hweight32(w) + __const_hweight32((w) >> 32))
         |                                                                            ^~
   include/asm-generic/bitops/const_hweight.h:10:16: note: in definition of macro '__const_hweight8'
      10 |          ((!!((w) & (1ULL << 0))) +     \
         |                ^
   include/asm-generic/bitops/const_hweight.h:20:31: note: in expansion of macro '__const_hweight16'
      20 | #define __const_hweight32(w) (__const_hweight16(w) + __const_hweight16((w) >> 16))
         |                               ^~~~~~~~~~~~~~~~~
   include/asm-generic/bitops/const_hweight.h:21:54: note: in expansion of macro '__const_hweight32'
      21 | #define __const_hweight64(w) (__const_hweight32(w) + __const_hweight32((w) >> 32))
         |                                                      ^~~~~~~~~~~~~~~~~
   include/asm-generic/bitops/const_hweight.h:29:49: note: in expansion of macro '__const_hweight64'
      29 | #define hweight64(w) (__builtin_constant_p(w) ? __const_hweight64(w) : __arch_hweight64(w))
         |                                                 ^~~~~~~~~~~~~~~~~
   arch/x86/kvm/hyperv.c:1983:36: note: in expansion of macro 'hweight64'
    1983 |                 if (hc->var_cnt != hweight64(valid_bank_mask))
         |                                    ^~~~~~~~~

CC: Borislav Petkov <bp@alien8.de>
CC: Dave Hansen <dave.hansen@linux.intel.com>
CC: H. Peter Anvin <hpa@zytor.com>
CC: Ingo Molnar <mingo@redhat.com>
CC: Jim Mattson <jmattson@google.com>
CC: Joerg Roedel <joro@8bytes.org>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Sean Christopherson <seanjc@google.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Vitaly Kuznetsov <vkuznets@redhat.com>
CC: Wanpeng Li <wanpengli@tencent.com>
CC: kvm@vger.kernel.org
CC: linux-kernel@vger.kernel.org
CC: x86@kernel.org
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Message-Id: <20220519171504.1238724-1-yury.norov@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index c964923..18325e0 100644 (file)
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1938,7 +1938,7 @@ static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
        struct hv_send_ipi_ex send_ipi_ex;
        struct hv_send_ipi send_ipi;
        DECLARE_BITMAP(vcpu_mask, KVM_MAX_VCPUS);
-       unsigned long valid_bank_mask;
+       u64 valid_bank_mask;
        u64 sparse_banks[KVM_HV_MAX_SPARSE_VCPU_SET_BITS];
        u32 vector;
        bool all_cpus;
@@ -1980,7 +1980,7 @@ static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
                valid_bank_mask = send_ipi_ex.vp_set.valid_bank_mask;
                all_cpus = send_ipi_ex.vp_set.format == HV_GENERIC_SET_ALL;
 
-               if (hc->var_cnt != bitmap_weight(&valid_bank_mask, 64))
+               if (hc->var_cnt != bitmap_weight((unsigned long *)&valid_bank_mask, 64))
                        return HV_STATUS_INVALID_HYPERCALL_INPUT;
 
                if (all_cpus)