linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: ira.weiny@intel.com
To: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>
Cc: Ira Weiny <ira.weiny@intel.com>,
	Sean Christopherson <seanjc@google.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	Fenghua Yu <fenghua.yu@intel.com>,
	linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: [PATCH V6 06/10] x86/fault: Adjust WARN_ON for PKey fault
Date: Thu,  1 Apr 2021 15:58:29 -0700	[thread overview]
Message-ID: <20210401225833.566238-7-ira.weiny@intel.com> (raw)
In-Reply-To: <20210401225833.566238-1-ira.weiny@intel.com>

From: Ira Weiny <ira.weiny@intel.com>

Previously if a Protection key fault occurred it indicated something
very wrong because user page mappings are not supposed to be in the
kernel address space.

Now PKey faults may happen on kernel mappings if the feature is enabled.

Remove the warning in the fault path and allow the oops to occur without
extra debugging if PKS is enabled.

Cc: Sean Christopherson <seanjc@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Changes from V5:
	From Dave Hansen
		Remove 'we' from comment

Changes from V4:
	From Sean Christopherson
		Clean up commit message and comment
		Change cpu_feature_enabled to be in WARN_ON check
---
 arch/x86/mm/fault.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index a73347e2cdfc..0e0e90968f57 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1141,11 +1141,15 @@ do_kern_addr_fault(struct pt_regs *regs, unsigned long hw_error_code,
 		   unsigned long address)
 {
 	/*
-	 * Protection keys exceptions only happen on user pages.  We
-	 * have no user pages in the kernel portion of the address
-	 * space, so do not expect them here.
+	 * X86_PF_PK (Protection key exceptions) may occur on kernel addresses
+	 * when PKS (PKeys Supervisor) is enabled.
+	 *
+	 * However, if PKS is not enabled WARN if this exception is seen
+	 * because there are no user pages in the kernel portion of the address
+	 * space.
 	 */
-	WARN_ON_ONCE(hw_error_code & X86_PF_PK);
+	WARN_ON_ONCE(!cpu_feature_enabled(X86_FEATURE_PKS) &&
+		     (hw_error_code & X86_PF_PK));
 
 #ifdef CONFIG_X86_32
 	/*
-- 
2.28.0.rc0.12.gb6a658bd00c9


  parent reply	other threads:[~2021-04-01 22:59 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-01 22:58 [PATCH V6 00/10] PKS: Add Protection Key Supervisor support ira.weiny
2021-04-01 22:58 ` [PATCH V6 01/10] x86/pkeys: Create pkeys_common.h ira.weiny
2021-04-01 22:58 ` [PATCH V6 02/10] x86/fpu: Refactor arch_set_user_pkey_access() for PKS support ira.weiny
2021-04-01 22:58 ` [PATCH V6 03/10] x86/pks: Add additional PKEY helper macros ira.weiny
2021-04-01 22:58 ` [PATCH V6 04/10] x86/pks: Add PKS defines and Kconfig options ira.weiny
2021-04-01 22:58 ` [PATCH V6 05/10] x86/pks: Add PKS setup code ira.weiny
2021-04-01 22:58 ` ira.weiny [this message]
2021-04-01 22:58 ` [PATCH V6 07/10] x86/pks: Preserve the PKRS MSR on context switch ira.weiny
2021-04-01 22:58 ` [PATCH V6 08/10] x86/entry: Preserve PKRS MSR across exceptions ira.weiny
2021-04-01 22:58 ` [PATCH V6 09/10] x86/pks: Add PKS kernel API ira.weiny
2021-04-01 22:58 ` [PATCH V6 10/10] x86/pks: Add PKS test code ira.weiny
2021-04-16 22:14 ` [PATCH V6 00/10] PKS: Add Protection Key Supervisor support Ira Weiny
2021-05-14 20:22   ` Ira Weiny

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=20210401225833.566238-7-ira.weiny@intel.com \
    --to=ira.weiny@intel.com \
    --cc=bp@alien8.de \
    --cc=dan.j.williams@intel.com \
    --cc=dave.hansen@linux.intel.com \
    --cc=fenghua.yu@intel.com \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-kselftest@vger.kernel.org \
    --cc=luto@kernel.org \
    --cc=mingo@redhat.com \
    --cc=peterz@infradead.org \
    --cc=seanjc@google.com \
    --cc=tglx@linutronix.de \
    --cc=x86@kernel.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).