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Date:   Fri, 15 Oct 2021 18:06:21 +0200
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Subject: Re: [PATCH] KVM: x86: Account for 32-bit kernels when handling
 address in TSC attrs
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To:     Oliver Upton <oupton@google.com>,
        Sean Christopherson <seanjc@google.com>
Cc:     Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20211007231647.3553604-1-seanjc@google.com>
 <CAOQ_Qsj9yiChnBZmotdYFYgsd=C0J5XXR8mthdiC+iXX22F7jw@mail.gmail.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
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On 11/10/21 16:35, Oliver Upton wrote:
> On Thu, Oct 7, 2021 at 6:16 PM Sean Christopherson <seanjc@google.com> wrote:
>>
>> When handling TSC attributes, cast the userspace provided virtual address
>> to an unsigned long before casting it to a pointer to fix warnings on
>> 32-bit kernels due to casting a 64-bit integer to a 32-bit pointer.
>>
>> Add a check that the truncated address matches the original address, e.g.
>> to prevent userspace specifying garbage in bits 63:32.
>>
>>    arch/x86/kvm/x86.c: In function ‘kvm_arch_tsc_get_attr’:
>>    arch/x86/kvm/x86.c:4947:22: error: cast to pointer from integer of different size
>>     4947 |  u64 __user *uaddr = (u64 __user *)attr->addr;
>>          |                      ^
>>    arch/x86/kvm/x86.c: In function ‘kvm_arch_tsc_set_attr’:
>>    arch/x86/kvm/x86.c:4967:22: error: cast to pointer from integer of different size
>>     4967 |  u64 __user *uaddr = (u64 __user *)attr->addr;
>>          |                      ^
>>
>> Cc: Oliver Upton <oupton@google.com>
>> Fixes: 469fde25e680 ("KVM: x86: Expose TSC offset controls to userspace")
>> Signed-off-by: Sean Christopherson <seanjc@google.com>
>> ---
>>   arch/x86/kvm/x86.c | 10 ++++++++--
>>   1 file changed, 8 insertions(+), 2 deletions(-)
>>
> 
> Reviewed-by: Oliver Upton <oupton@google.com>
> 

Squashed, thanks.

Paolo