All of lore.kernel.org
 help / color / mirror / Atom feed
From: Alexey Kardashevskiy <aik@ozlabs.ru>
To: linuxppc-dev@lists.ozlabs.org
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>,
	Frederic Barrat <fbarrat@linux.ibm.com>,
	kvm-ppc@vger.kernel.org, kvm@vger.kernel.org
Subject: [PATCH kernel] KVM: PPC: Do not warn when userspace asked for too big TCE table
Date: Tue, 28 Jun 2022 18:02:28 +1000	[thread overview]
Message-ID: <20220628080228.1508847-1-aik@ozlabs.ru> (raw)

KVM manages emulated TCE tables for guest LIOBNs by a two level table
which maps up to 128TiB with 16MB IOMMU pages (enabled in QEMU by default)
and MAX_ORDER=11 (the kernel's default). Note that the last level of
the table is allocated when actual TCE is updated.

However these tables are created via ioctl() on kvmfd and the userspace
can trigger WARN_ON_ONCE_GFP(order >= MAX_ORDER, gfp) in mm/page_alloc.c
and flood dmesg.

This adds __GFP_NOWARN.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---

We could probably switch to vmalloc() to allow even bigger
emulated tables which we do not really want the userspace
to create though.

---
 arch/powerpc/kvm/book3s_64_vio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c
index d6589c4fe889..40864373ef87 100644
--- a/arch/powerpc/kvm/book3s_64_vio.c
+++ b/arch/powerpc/kvm/book3s_64_vio.c
@@ -307,7 +307,7 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
 		return ret;
 
 	ret = -ENOMEM;
-	stt = kzalloc(struct_size(stt, pages, npages), GFP_KERNEL);
+	stt = kzalloc(struct_size(stt, pages, npages), GFP_KERNEL | __GFP_NOWARN);
 	if (!stt)
 		goto fail_acct;
 
-- 
2.30.2


WARNING: multiple messages have this Message-ID (diff)
From: Alexey Kardashevskiy <aik@ozlabs.ru>
To: linuxppc-dev@lists.ozlabs.org
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>,
	Frederic Barrat <fbarrat@linux.ibm.com>,
	kvm@vger.kernel.org, kvm-ppc@vger.kernel.org
Subject: [PATCH kernel] KVM: PPC: Do not warn when userspace asked for too big TCE table
Date: Tue, 28 Jun 2022 18:02:28 +1000	[thread overview]
Message-ID: <20220628080228.1508847-1-aik@ozlabs.ru> (raw)

KVM manages emulated TCE tables for guest LIOBNs by a two level table
which maps up to 128TiB with 16MB IOMMU pages (enabled in QEMU by default)
and MAX_ORDER=11 (the kernel's default). Note that the last level of
the table is allocated when actual TCE is updated.

However these tables are created via ioctl() on kvmfd and the userspace
can trigger WARN_ON_ONCE_GFP(order >= MAX_ORDER, gfp) in mm/page_alloc.c
and flood dmesg.

This adds __GFP_NOWARN.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---

We could probably switch to vmalloc() to allow even bigger
emulated tables which we do not really want the userspace
to create though.

---
 arch/powerpc/kvm/book3s_64_vio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c
index d6589c4fe889..40864373ef87 100644
--- a/arch/powerpc/kvm/book3s_64_vio.c
+++ b/arch/powerpc/kvm/book3s_64_vio.c
@@ -307,7 +307,7 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
 		return ret;
 
 	ret = -ENOMEM;
-	stt = kzalloc(struct_size(stt, pages, npages), GFP_KERNEL);
+	stt = kzalloc(struct_size(stt, pages, npages), GFP_KERNEL | __GFP_NOWARN);
 	if (!stt)
 		goto fail_acct;
 
-- 
2.30.2


WARNING: multiple messages have this Message-ID (diff)
From: Alexey Kardashevskiy <aik@ozlabs.ru>
To: linuxppc-dev@lists.ozlabs.org
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>,
	Frederic Barrat <fbarrat@linux.ibm.com>,
	kvm-ppc@vger.kernel.org, kvm@vger.kernel.org
Subject: [PATCH kernel] KVM: PPC: Do not warn when userspace asked for too big TCE table
Date: Tue, 28 Jun 2022 08:02:28 +0000	[thread overview]
Message-ID: <20220628080228.1508847-1-aik@ozlabs.ru> (raw)

KVM manages emulated TCE tables for guest LIOBNs by a two level table
which maps up to 128TiB with 16MB IOMMU pages (enabled in QEMU by default)
and MAX_ORDER\x11 (the kernel's default). Note that the last level of
the table is allocated when actual TCE is updated.

However these tables are created via ioctl() on kvmfd and the userspace
can trigger WARN_ON_ONCE_GFP(order >= MAX_ORDER, gfp) in mm/page_alloc.c
and flood dmesg.

This adds __GFP_NOWARN.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---

We could probably switch to vmalloc() to allow even bigger
emulated tables which we do not really want the userspace
to create though.

---
 arch/powerpc/kvm/book3s_64_vio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c
index d6589c4fe889..40864373ef87 100644
--- a/arch/powerpc/kvm/book3s_64_vio.c
+++ b/arch/powerpc/kvm/book3s_64_vio.c
@@ -307,7 +307,7 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
 		return ret;
 
 	ret = -ENOMEM;
-	stt = kzalloc(struct_size(stt, pages, npages), GFP_KERNEL);
+	stt = kzalloc(struct_size(stt, pages, npages), GFP_KERNEL | __GFP_NOWARN);
 	if (!stt)
 		goto fail_acct;
 
-- 
2.30.2

             reply	other threads:[~2022-06-28  8:03 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-28  8:02 Alexey Kardashevskiy [this message]
2022-06-28  8:02 ` [PATCH kernel] KVM: PPC: Do not warn when userspace asked for too big TCE table Alexey Kardashevskiy
2022-06-28  8:02 ` Alexey Kardashevskiy
2022-07-09 10:14 ` Michael Ellerman
2022-07-09 10:14   ` Michael Ellerman
2022-07-09 10:14   ` Michael Ellerman

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20220628080228.1508847-1-aik@ozlabs.ru \
    --to=aik@ozlabs.ru \
    --cc=fbarrat@linux.ibm.com \
    --cc=kvm-ppc@vger.kernel.org \
    --cc=kvm@vger.kernel.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.