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Shutemov" To: Borislav Petkov Cc: Tom Lendacky , linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, iommu@lists.linux-foundation.org, kvm@vger.kernel.org, linux-efi@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-graphics-maintainer@vmware.com, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, Brijesh Singh , Joerg Roedel , Andi Kleen , Sathyanarayanan Kuppuswamy , Tianyu Lan , Christoph Hellwig , Thomas Gleixner , Ingo Molnar , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Will Deacon Subject: Re: [PATCH v3 5/8] x86/sme: Replace occurrences of sme_active() with cc_platform_has() Message-ID: <20210922210558.itofvu3725dap5xx@box.shutemov.name> References: <77df37e1-0496-aed5-fd1d-302180f1edeb@amd.com> <20210921212059.wwlytlmxoft4cdth@box.shutemov.name> <20210921213401.i2pzaotgjvn4efgg@box.shutemov.name> <00f52bf8-cbc6-3721-f40e-2f51744751b0@amd.com> <20210921215830.vqxd75r4eyau6cxy@box.shutemov.name> <01891f59-7ec3-cf62-a8fc-79f79ca76587@amd.com> <20210922143015.vvxvh6ec73lffvkf@box.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 22, 2021 at 09:52:07PM +0200, Borislav Petkov wrote: > On Wed, Sep 22, 2021 at 05:30:15PM +0300, Kirill A. Shutemov wrote: > > Not fine, but waiting to blowup with random build environment change. > > Why is it not fine? > > Are you suspecting that the compiler might generate something else and > not a rip-relative access? Yes. We had it before for __supported_pte_mask and other users of fixup_pointer(). See for instance 4a09f0210c8b ("x86/boot/64/clang: Use fixup_pointer() to access '__supported_pte_mask'") Unless we find other way to guarantee RIP-relative access, we must use fixup_pointer() to access any global variables. -- Kirill A. Shutemov