From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8855119D071; Tue, 10 Mar 2026 01:29:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.12 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773106192; cv=none; b=PcVSsIYQa2TPQBKr5hggLoV+YuaUUfDuOXbPNnKr/aDSqJ/5Rj3kEvTUNQDghXVYDYbIGZfh2BeeIP2vODm/Z/4AWEM8+W3jV90d457V4O+teJznhW8w178oSuIfzCPoXjdJ014qaaCch6W9T1spwE8m4+KVQJf6r02SwB/89eA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773106192; c=relaxed/simple; bh=gz43Mj2oXlYu+w6zv6iXQcm0PwcTvoq9HfUZw6RWieE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Q3Nj4qarbmNfIu4rbkbFjV6y7/MCR3oqr9RMK8ld8ZGVrLQJqIjrlGQtqsnWNXhH65+b6d3AK2hRiBPsiCtQJPocfyhyjfeV+Qump0dqYbLj8YTWkrtBtfdryDVZ0Aamrh47gCdMVBGDpWhNpNhcywWMm7CX+vfOxEPOWuM9xbI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Iw9hR1eX; arc=none smtp.client-ip=198.175.65.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Iw9hR1eX" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1773106192; x=1804642192; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=gz43Mj2oXlYu+w6zv6iXQcm0PwcTvoq9HfUZw6RWieE=; b=Iw9hR1eXGsNpOYpbUMAOUQBj1bwu3JbKB18e5/TLDjQsVn9PgMNIJnfO OgbNPoM1filxdUicB2it3uniNxXW0MvQpBMa7M7cZ91UFJDpklYysDUuG AqWnLw63bdV15WMuSlZzdSJBNGj9gObTWt6777x/dBCxEwWWKWgULMgjH BMurrZC5w6uClZZ6XGZNRTSq8llDQdtjAKaQR0bxfwKYGhHfCRWnCsALt I5yO4yOgZrWzmKiHSI2/aEm4Cm6vp117ShZRDktsc44LrbF80k8oFVBAV OLbokWXsHbArANdR5pg+2RiTWFxDZXoe/0CjW0DYfg+CCRsFwiFEZ+Z2Q w==; X-CSE-ConnectionGUID: DBLrUxOpSIeUP1/ueHpQjw== X-CSE-MsgGUID: fROjqRBKTaaOttr0sSfVMQ== X-IronPort-AV: E=McAfee;i="6800,10657,11724"; a="85619075" X-IronPort-AV: E=Sophos;i="6.23,111,1770624000"; d="scan'208";a="85619075" Received: from fmviesa006.fm.intel.com ([10.60.135.146]) by orvoesa104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Mar 2026 18:29:51 -0700 X-CSE-ConnectionGUID: XbYawSbvS/qxFZEU60kr8g== X-CSE-MsgGUID: AZ7OPRmWRyeOqF922POAQw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.23,111,1770624000"; d="scan'208";a="216378204" Received: from unknown (HELO [10.238.1.107]) ([10.238.1.107]) by fmviesa006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Mar 2026 18:29:49 -0700 Message-ID: <5a1fb240-1806-420c-bf30-8789752aa717@intel.com> Date: Tue, 10 Mar 2026 09:29:46 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] KVM: x86/tdp_mmu: Fix base gfn check when zapping private huge SPTE To: Sean Christopherson , pcjer Cc: kvm@vger.kernel.org, pbonzini@redhat.com, linux-kernel@vger.kernel.org References: <20260309083844.217215-1-pcj3195161583@163.com> Content-Language: en-US From: Xiaoyao Li In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 3/9/2026 10:23 PM, Sean Christopherson wrote: > On Mon, Mar 09, 2026, pcjer wrote: >> Signed-off-by: pcjer >> --- >> arch/x86/kvm/mmu/tdp_mmu.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c >> index 1266d5452..8482a85d6 100644 >> --- a/arch/x86/kvm/mmu/tdp_mmu.c >> +++ b/arch/x86/kvm/mmu/tdp_mmu.c >> @@ -1025,8 +1025,8 @@ static bool tdp_mmu_zap_leafs(struct kvm *kvm, struct kvm_mmu_page *root, >> >> slot = gfn_to_memslot(kvm, gfn); >> if (kvm_hugepage_test_mixed(slot, gfn, iter.level) || >> - (gfn & mask) < start || >> - end < (gfn & mask) + KVM_PAGES_PER_HPAGE(iter.level)) { >> + (gfn & ~mask) < start || >> + end < (gfn & ~mask) + KVM_PAGES_PER_HPAGE(iter.level)) { > > Somewhat to my surprise, this does indeed look like a legitimate fix, ignoring > that the code in question was never merged and was lasted posted 2+ years ago[*] > (and has long since been replaced). > > The bug likely went unnoticed during development because "(gfn & mask) < start" > would almost always be true (mask == 511 for a 2MiB page). Though mask should > really just be inverted from the get go in this code > > + if (is_private && kvm_gfn_shared_mask(kvm) && > + is_large_pte(iter.old_spte)) { > + gfn_t gfn = iter.gfn & ~kvm_gfn_shared_mask(kvm); > + gfn_t mask = KVM_PAGES_PER_HPAGE(iter.level) - 1; > + > + struct kvm_memory_slot *slot; > + struct kvm_mmu_page *sp; > + > > [*] https://lore.kernel.org/all/c656573ccc68e212416d323d35f884bff25e6e2d.1708933624.git.isaku.yamahata@intel.com > /faceplam, the buggy code was written by me.