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: <51eeb843-204f-5b9d-9f7f-9bf3c22d2c00@intel.com>
Date:   Tue, 27 Sep 2022 10:10:54 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Tom Lendacky <thomas.lendacky@....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 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?

> 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);
> };