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Date:   Thu, 4 Feb 2021 23:13:18 +0100
From:   Borislav Petkov <bp@alien8.de>
To:     Arvind Sankar <nivedita@alum.mit.edu>
Cc:     Ard Biesheuvel <ardb@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Arnd Bergmann <arnd@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, X86 ML <x86@kernel.org>,
        Nathan Chancellor <natechancellor@gmail.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Darren Hart <dvhart@infradead.org>,
        Andy Shevchenko <andy@infradead.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        linux-efi <linux-efi@vger.kernel.org>,
        platform-driver-x86@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH] x86: efi: avoid BUILD_BUG_ON() for non-constant p4d_index
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On Thu, Feb 04, 2021 at 04:43:58PM -0500, Arvind Sankar wrote:
> This should check EFI_VA_END instead of EFI_VA_START, and maybe throw in
> a BUG_ON if EFI_VA_END >= EFI_VA_START.

No need:

        if (efi_va < EFI_VA_END) {
                pr_warn(FW_WARN "VA address range overflow!\n");
                return;
        }

We already check we're not going over at map time. And our runtime
services range is hardcoded. And we're switching to that PGD on each
runtime services call.

So I don't see the point for keeping any of the assertions.

Unless you have other valid arguments for keeping them...

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette