From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yw1-f202.google.com (mail-yw1-f202.google.com [209.85.128.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D04D214A86 for ; Wed, 19 Jul 2023 15:39:11 +0000 (UTC) Received: by mail-yw1-f202.google.com with SMTP id 00721157ae682-583312344e7so41914997b3.1 for ; Wed, 19 Jul 2023 08:39:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1689781150; x=1692373150; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=3uTGEOgXGgjS1mpy4uY8Zn88ggwsAyaWY3/MU5WFUXU=; b=zuZWZV29hv7HoMETiCkSKGIHZcpHTMG8TKF9qduMPPS/E1c0SfFLVA6kGEOoP5U9qq U77CuEsLMMxKIxLMFnjtp2hpB+IIMkYXVFGsPC5bapP3nIk/nGTrjqlCGcZf5+xPpr8T q16/aDqhEkgnoKMdGaA5rz+Gt+5uK6D6P1fr5Zm7R4i7YF7l973NWOrr+c3kq7IzyS9M gLZmugAwtecTQMKF7z0UBcPf86RbNReN6ZSKfaBS2Zp8N7kJnMwhsDMUzBHIndlxccW1 lnFRHUcOrryTZsXwruMmKL2jJUIvic1/Jzr/kaZBJYZOlvirf0tEwgFNXnc0yrJBGF6s gFpQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689781150; x=1692373150; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=3uTGEOgXGgjS1mpy4uY8Zn88ggwsAyaWY3/MU5WFUXU=; b=MWGEDIpQeRna3Ti0fKGxRGGIpcItV2Zy9OcxVCFyJbt+sPIm2Femyfi4M3l91aaPll MyDdbNLQh3xKt7Qnf1iwu2nZqeeDTaepEWVYXhmOuVqCg/Jrsr4kWBZU1rIENyRl+GxA +mRvavVC/p/NFORv9jtxVCxTDItIXDqN+YmKPpuFNSNib+svxB2dCas/nyNIa2Dog1zp LRNTdI/AZndkogwhb2Fg/8n+/soS27FehokRgiwg76jcWl+aRQS2ZnG8PovKUltAhCbs J95SAz46G4FnWHC+LYruLqle419ZL19k5PfV0ILf+IX1UCm543/CaTx8FJPfCXb/CQfw ADyw== X-Gm-Message-State: ABy/qLZbHO1YjDf5aIG6oT03jt8WPZmXlTo771LTlGi3lvKT6qcpvkp2 vzfFRHGGRJUZBp5tsrjMvg7wbFApCfI= X-Google-Smtp-Source: APBJJlHKX/op8BIXr6hrdN4x6RovTyUJBoPmA+F//tB9wdB4uZjaG/yxyF0KPogxnGD6eEZAy2DX7qXfLUE= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a25:868b:0:b0:c4d:9831:9712 with SMTP id z11-20020a25868b000000b00c4d98319712mr26898ybk.0.1689781150625; Wed, 19 Jul 2023 08:39:10 -0700 (PDT) Date: Wed, 19 Jul 2023 08:39:09 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20230718234512.1690985-1-seanjc@google.com> <20230718234512.1690985-2-seanjc@google.com> Message-ID: Subject: Re: [RFC PATCH v11 01/29] KVM: Wrap kvm_gfn_range.pte in a per-action union From: Sean Christopherson To: Jarkko Sakkinen Cc: Paolo Bonzini , Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , "Matthew Wilcox (Oracle)" , Andrew Morton , Paul Moore , James Morris , "Serge E. Hallyn" , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Chao Peng , Fuad Tabba , Yu Zhang , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , Vlastimil Babka , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A . Shutemov" Content-Type: text/plain; charset="us-ascii" On Wed, Jul 19, 2023, Jarkko Sakkinen wrote: > On Wed Jul 19, 2023 at 2:44 AM EEST, Sean Christopherson wrote: > > /* Huge pages aren't expected to be modified without first being zapped. */ > > - WARN_ON(pte_huge(range->pte) || range->start + 1 != range->end); > > + WARN_ON(pte_huge(range->arg.pte) || range->start + 1 != range->end); > > Not familiar with this code. Just checking whether whether instead > pr_{warn,err}() The "full" WARN is desirable, this is effecitvely an assert on the contract between the primary MMU, generic KVM code, and x86's TDP MMU. The .change_pte() mmu_notifier callback doesn't allow for hugepages, i.e. it's a (likely fatal) kernel bug if a hugepage is encountered at this point. Ditto for the "start + 1 == end" check, if that fails then generic KVM likely has a fatal bug. > combined with return false would be a more graceful option? The return value communicates whether or not a TLB flush is needed, not whether or not the operation was successful, i.e. there is no way to cancel the unexpected PTE change.