From nobody Wed Dec 17 12:06:29 2025 Received: from mail-ua1-f73.google.com (mail-ua1-f73.google.com [209.85.222.73]) (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 E8FEC16C862 for ; Wed, 10 Jul 2024 23:42:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720654976; cv=none; b=L99c3/H+E2yf/ep0MuW2jT8tKcZ0uhJDYe64DlSEzIkKPlPgf/hiUkFWERUYEKfCLILsFkbaGBMMmK14ls0M9rF4fTgdVmhso+o7BQraEnNbs2WdvPdqaCk7rKAVu3t5mGMoswFlV/RYJ9+yPskDuEwAg/j+rMCi7oNV8ltxnxg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720654976; c=relaxed/simple; bh=9nGVvjTtRrzXeDKQT/PGApCposmumXI12BdKtg64Aj8=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=sr0MBajdDkIvG7PwjziK7ZMJZz5b7PbNJe8Uib896oF+5WF32ycObu9mTUFboxSxXOHgzuAM4eFggLn9/lxg68HkkKG4NzSEEsRD4Br35hmCqp40DUD+aXC9mWDSUIiOYVb444Gs3novJ5BBfb6FKoTVeIUaIFHl2dJgv+QuGSs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--jthoughton.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=gDXVRsCx; arc=none smtp.client-ip=209.85.222.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--jthoughton.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="gDXVRsCx" Received: by mail-ua1-f73.google.com with SMTP id a1e0cc1a2514c-8101ef99bf6so89288241.0 for ; Wed, 10 Jul 2024 16:42:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1720654973; x=1721259773; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=86wUnUhZHhvP2m3KtD2mzNoNsfKZM3y2BVe++0uTyFA=; b=gDXVRsCx4zAb+aXQVU500pfuxdZC1fBEA1iLF/nd/5kaJzmrZvl9SDY2pHegNlDieX hd8gLixD2Jl+++LLsALferKZDuhbA1PzIJmVwFM8Wxmp/scWJlgpfU4AOkD3t3ObKRst OenkqnPb3tJdCOiWX2bVSr6jwWzDTB9i8nH3LgleIWgOGXl/Rttrre+zbPV0eS4/jV7t GxzpanKaknmyn08V6EwDg4rLCLeQnOEpfQJwuOgWAkBzMg1JhsnWXn8AFPs44QJP8Z5X 4VhbUFc2EcLF1yjqiDWBwv3TuwVIiYFgdsjHaSSKoewzwiQlIBfCLxwee5mFwULOgDOb 40LA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1720654973; x=1721259773; 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=86wUnUhZHhvP2m3KtD2mzNoNsfKZM3y2BVe++0uTyFA=; b=vKYMC8MOodW50jELNSdqCFphvPyG38jsPXDO9klGzwKEe8FnKiAf1QxIXsvu4MI5l9 1/aCm0cL9CND70kFJImh7lsVdJM/bSD7/SdU1kZNhNEg/FOPp72D5NXN7us0jnVXVNUR CVcMJOVyrQMmL/r1hyHtzbkvFleizGl61p2Q8zxWwJaETrpW3K5EaS+LcgjyfkBPtuxp MJtBZOQHOKwqDohN4wnDYWVEuri5WE9hn/zO0YWmC6zEwgtrDz7eaWBaW6ucW8Sf0IdY B3QesvmfmqZb8qSn2jcb8CdzV9S5zz22IBbeVxix1CPXewLD33y2nGCTbJVRT1lD1Wwz Q8nw== X-Forwarded-Encrypted: i=1; AJvYcCVgw8ijsT7PS4tKyHShGEvRSZFLDXmtEGZCGtbsXQLHaWyKplcLyms8zhxeZhkEaBr9CB9UiVGeOBtd9BG0+y+YnRsJC/74NFzl6WRt X-Gm-Message-State: AOJu0YwMX3038dKo3rbtR2FLNuhKo5GDmUgnMw4YOoei0oAIv5yITxuo Nzl+38n6+7SFziOZfB4lu4OLj3xKBiAvaQ+xR7Z3H1XT18ZQsie/j5havwWEWQOeTaA3Z6qfwzx a1YHT39qU2WltmQzYlg== X-Google-Smtp-Source: AGHT+IFuuD8TX5cMTXqfbBITU1Rk5gbgp8/gjNqtfzjUDzjMtEhdHehLKT0HBMd1mO2mStlwTdwfc0NYjYZ51/Zs X-Received: from jthoughton.c.googlers.com ([fda3:e722:ac3:cc00:14:4d90:c0a8:2a4f]) (user=jthoughton job=sendgmr) by 2002:a05:6130:2c07:b0:80f:e89a:dc21 with SMTP id a1e0cc1a2514c-81076f04ee0mr30519241.2.1720654972976; Wed, 10 Jul 2024 16:42:52 -0700 (PDT) Date: Wed, 10 Jul 2024 23:42:19 +0000 In-Reply-To: <20240710234222.2333120-1-jthoughton@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240710234222.2333120-1-jthoughton@google.com> X-Mailer: git-send-email 2.45.2.993.g49e7a77208-goog Message-ID: <20240710234222.2333120-16-jthoughton@google.com> Subject: [RFC PATCH 15/18] KVM: guest_memfd: Add KVM Userfault support From: James Houghton To: Paolo Bonzini Cc: Marc Zyngier , Oliver Upton , James Morse , Suzuki K Poulose , Zenghui Yu , Sean Christopherson , Shuah Khan , Peter Xu , Axel Rasmussen , David Matlack , James Houghton , kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" We now have to pass our struct kvm into __kvm_gmem_get_pfn to know if a gfn is userfault-enabled or not. For faults on userfault-enabled gfns, indicate this to the caller by setting *pfn to KVM_PFN_ERR_USERFAULT. Architectures may use this to know to return a userfault to userspace, though they should be careful to set a value for *pfn before calling (e.g. KVM_PFN_ERR_FAULT). While we're at it, set *pfn to KVM_PFN_ERR_HWPOISON for accesses to poisoned gfns. Signed-off-by: James Houghton --- virt/kvm/guest_memfd.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 9148b9679bb1..ba7a981e3396 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -542,8 +542,9 @@ void kvm_gmem_unbind(struct kvm_memory_slot *slot) fput(file); } =20 -static int __kvm_gmem_get_pfn(struct file *file, struct kvm_memory_slot *s= lot, - gfn_t gfn, kvm_pfn_t *pfn, int *max_order, bool prepare) +static int __kvm_gmem_get_pfn(struct kvm *kvm, struct file *file, + struct kvm_memory_slot *slot, gfn_t gfn, kvm_pfn_t *pfn, + int *max_order, bool prepare) { pgoff_t index =3D gfn - slot->base_gfn + slot->gmem.pgoff; struct kvm_gmem *gmem =3D file->private_data; @@ -551,6 +552,11 @@ static int __kvm_gmem_get_pfn(struct file *file, struc= t kvm_memory_slot *slot, struct page *page; int r; =20 + if (gfn_has_userfault(kvm, gfn)) { + *pfn =3D KVM_PFN_ERR_USERFAULT; + return -EFAULT; + } + if (file !=3D slot->gmem.file) { WARN_ON_ONCE(slot->gmem.file); return -EFAULT; @@ -567,6 +573,7 @@ static int __kvm_gmem_get_pfn(struct file *file, struct= kvm_memory_slot *slot, return PTR_ERR(folio); =20 if (folio_test_hwpoison(folio)) { + *pfn =3D KVM_PFN_ERR_HWPOISON; folio_unlock(folio); folio_put(folio); return -EHWPOISON; @@ -594,7 +601,7 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory= _slot *slot, if (!file) return -EFAULT; =20 - r =3D __kvm_gmem_get_pfn(file, slot, gfn, pfn, max_order, true); + r =3D __kvm_gmem_get_pfn(kvm, file, slot, gfn, pfn, max_order, true); fput(file); return r; } @@ -634,7 +641,8 @@ long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn= , void __user *src, long break; } =20 - ret =3D __kvm_gmem_get_pfn(file, slot, gfn, &pfn, &max_order, false); + ret =3D __kvm_gmem_get_pfn(kvm, file, slot, gfn, &pfn, + &max_order, false); if (ret) break; =20 --=20 2.45.2.993.g49e7a77208-goog