linux-kernel - Re: [PATCH v5 1/6] x86/sev: Fix calculation of end address based on number of pages

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Message-ID: <30026d7b-a736-5660-2e5e-7e9fcef10101@amd.com>
Date:   Tue, 27 Sep 2022 15:45:49 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Dave Hansen <dave.hansen@...el.com>, linux-kernel@...r.kernel.org,
        x86@...nel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        "H. Peter Anvin" <hpa@...or.com>,
        Michael Roth <michael.roth@....com>,
        Joerg Roedel <jroedel@...e.de>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v5 1/6] x86/sev: Fix calculation of end address based on
 number of pages

On 9/27/22 12:10, Dave Hansen wrote:
> On 9/27/22 10:04, Tom Lendacky wrote:
>> --- a/arch/x86/kernel/sev.c
>> +++ b/arch/x86/kernel/sev.c
>> @@ -649,7 +649,7 @@ static void pvalidate_pages(unsigned long vaddr, unsigned int npages, bool valid
>>   	int rc;
>>   
>>   	vaddr = vaddr & PAGE_MASK;
>> -	vaddr_end = vaddr + (npages << PAGE_SHIFT);
>> +	vaddr_end = vaddr + ((unsigned long)npages << PAGE_SHIFT);
> 
> Could we please just fix the fragile typing that cascaded down to this
> point?
> 
> Shouldn't 'npages' in this interface be a long?

I'll take a look at that.

Thanks,
Tom

> 
>> struct x86_guest {
>>          void (*enc_status_change_prepare)(unsigned long vaddr, int npages, bool enc);
>>          bool (*enc_status_change_finish)(unsigned long vaddr, int npages, bool enc);
>>          bool (*enc_tlb_flush_required)(bool enc);
>>          bool (*enc_cache_flush_required)(void);
>> };