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Wed, 3 Dec 2025 21:18:20 +0000 (UTC) Date: Wed, 3 Dec 2025 22:18:13 +0100 From: Borislav Petkov To: Steven Noonan Cc: linux-kernel@vger.kernel.org, Ariadne Conill , Yazen Ghannam , x86@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 1/2] x86/amd_node: fix integer divide by zero during init Message-ID: <20251203211813.GAaTCpFeDir7jXkEPf@fat_crate.local> References: <20251114195730.1503879-1-steven@uplinklabs.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20251114195730.1503879-1-steven@uplinklabs.net> On Fri, Nov 14, 2025 at 07:57:35PM +0000, Steven Noonan wrote: > On a Xen dom0 boot, this feature does not behave, and we end up > calculating: > > num_roots = 1 > num_nodes = 2 > roots_per_node = 0 > > This causes a divide-by-zero in the modulus inside the loop. > > This change adds a couple of guards for invalid states where we might > get a divide-by-zero. > > Signed-off-by: Steven Noonan > Signed-off-by: Ariadne Conill > CC: Yazen Ghannam > CC: x86@vger.kernel.org > CC: stable@vger.kernel.org > --- > arch/x86/kernel/amd_node.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c > index 3d0a4768d603c..cdc6ba224d4ad 100644 > --- a/arch/x86/kernel/amd_node.c > +++ b/arch/x86/kernel/amd_node.c > @@ -282,6 +282,17 @@ static int __init amd_smn_init(void) That better not be loading at all on a X86_FEATURE_HYPERVISOR configuration. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette