From: ira.weiny@intel.com
To: Dave Hansen <dave.hansen@linux.intel.com>,
Dan Williams <dan.j.williams@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
nvdimm@lists.linux.dev, linux-mm@kvack.org
Subject: [PATCH V7 07/18] x86/pks: Preserve the PKRS MSR on context switch
Date: Tue, 3 Aug 2021 21:32:20 -0700 [thread overview]
Message-ID: <20210804043231.2655537-8-ira.weiny@intel.com> (raw)
In-Reply-To: <20210804043231.2655537-1-ira.weiny@intel.com>
From: Ira Weiny <ira.weiny@intel.com>
The PKRS MSR is defined as a per-logical-processor register. This
isolates memory access by logical CPU. Unfortunately, the MSR is not
managed by XSAVE. Therefore, tasks must save/restore the MSR value on
context switch.
Define a saved PKRS value in the task struct. Initialize all tasks with
the INIT_PKRS_VALUE and call pkrs_write_current() to set the MSR to the
saved task value on schedule in.
Co-developed-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
---
Changes for V7
Move definitions from asm/processor.h to asm/pks.h
s/INIT_PKRS_VALUE/pkrs_init_value
Change pks_init_task()/pks_sched_in() to functions
s/pks_sched_in/pks_write_current to be used more generically
later in the series
---
arch/x86/include/asm/pks.h | 4 ++++
arch/x86/include/asm/processor.h | 19 ++++++++++++++++++-
arch/x86/kernel/process.c | 3 +++
arch/x86/kernel/process_64.c | 3 +++
arch/x86/mm/pkeys.c | 16 ++++++++++++++++
5 files changed, 44 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/pks.h b/arch/x86/include/asm/pks.h
index 5d7067ada8fb..e7727086cec2 100644
--- a/arch/x86/include/asm/pks.h
+++ b/arch/x86/include/asm/pks.h
@@ -5,10 +5,14 @@
#ifdef CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS
void setup_pks(void);
+void pkrs_write_current(void);
+void pks_init_task(struct task_struct *task);
#else /* !CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS */
static inline void setup_pks(void) { }
+static inline void pkrs_write_current(void) { }
+static inline void pks_init_task(struct task_struct *task) { }
#endif /* CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS */
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index f3020c54e2cb..a6cb7d152c62 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -502,6 +502,12 @@ struct thread_struct {
unsigned long cr2;
unsigned long trap_nr;
unsigned long error_code;
+
+#ifdef CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS
+ /* Saved Protection key register for supervisor mappings */
+ u32 saved_pkrs;
+#endif
+
#ifdef CONFIG_VM86
/* Virtual 86 mode info */
struct vm86 *vm86;
@@ -768,7 +774,18 @@ static inline void spin_lock_prefetch(const void *x)
#define KSTK_ESP(task) (task_pt_regs(task)->sp)
#else
-#define INIT_THREAD { }
+
+#ifdef CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS
+/*
+ * Early task gets full permissions, the restrictive value is set in
+ * pks_init_task()
+ */
+#define INIT_THREAD { \
+ .saved_pkrs = 0, \
+}
+#else
+#define INIT_THREAD { }
+#endif
extern unsigned long KSTK_ESP(struct task_struct *task);
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 1d9463e3096b..c792ac5f33a2 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -43,6 +43,7 @@
#include <asm/io_bitmap.h>
#include <asm/proto.h>
#include <asm/frame.h>
+#include <asm/pks.h>
#include "process.h"
@@ -223,6 +224,8 @@ void flush_thread(void)
fpu_flush_thread();
pkru_flush_thread();
+
+ pks_init_task(tsk);
}
void disable_TSC(void)
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index ec0d836a13b1..8bd1f039e5bf 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -59,6 +59,7 @@
/* Not included via unistd.h */
#include <asm/unistd_32_ia32.h>
#endif
+#include <asm/pks.h>
#include "process.h"
@@ -658,6 +659,8 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
/* Load the Intel cache allocation PQR MSR. */
resctrl_sched_in();
+ pkrs_write_current();
+
return prev_p;
}
diff --git a/arch/x86/mm/pkeys.c b/arch/x86/mm/pkeys.c
index fbffbced81b5..eca01dc8d7ac 100644
--- a/arch/x86/mm/pkeys.c
+++ b/arch/x86/mm/pkeys.c
@@ -284,5 +284,21 @@ void setup_pks(void)
write_pkrs(pkrs_init_value);
cr4_set_bits(X86_CR4_PKS);
}
+;
+
+/*
+ * PKRS is only temporarily changed during specific code paths. Only a
+ * preemption during these windows away from the default value would
+ * require updating the MSR. write_pkrs() handles this optimization.
+ */
+void pkrs_write_current(void)
+{
+ write_pkrs(current->thread.saved_pkrs);
+}
+
+void pks_init_task(struct task_struct *task)
+{
+ task->thread.saved_pkrs = pkrs_init_value;
+}
#endif /* CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS */
--
2.28.0.rc0.12.gb6a658bd00c9
next prev parent reply other threads:[~2021-08-04 4:32 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-04 4:32 [PATCH V7 00/18] PKS/PMEM: Add Stray Write Protection ira.weiny
2021-08-04 4:32 ` [PATCH V7 01/18] x86/pkeys: Create pkeys_common.h ira.weiny
2021-08-04 4:32 ` [PATCH V7 02/18] x86/fpu: Refactor arch_set_user_pkey_access() ira.weiny
2021-11-25 14:23 ` Thomas Gleixner
2021-08-04 4:32 ` [PATCH V7 03/18] x86/pks: Add additional PKEY helper macros ira.weiny
2021-11-25 14:25 ` Thomas Gleixner
2021-11-25 16:58 ` Thomas Gleixner
2021-12-08 0:51 ` Ira Weiny
2021-12-08 15:11 ` Thomas Gleixner
2021-08-04 4:32 ` [PATCH V7 04/18] x86/pks: Add PKS defines and Kconfig options ira.weiny
2021-08-04 4:32 ` [PATCH V7 05/18] x86/pks: Add PKS setup code ira.weiny
2021-11-25 15:15 ` Thomas Gleixner
2021-11-26 3:11 ` taoyi.ty
2021-11-26 9:57 ` Thomas Gleixner
2021-11-26 11:03 ` Thomas Gleixner
2021-08-04 4:32 ` [PATCH V7 06/18] x86/fault: Adjust WARN_ON for PKey fault ira.weiny
2021-08-04 4:32 ` ira.weiny [this message]
2021-11-25 15:25 ` [PATCH V7 07/18] x86/pks: Preserve the PKRS MSR on context switch Thomas Gleixner
2021-08-04 4:32 ` [PATCH V7 08/18] x86/entry: Preserve PKRS MSR across exceptions ira.weiny
2021-11-13 0:50 ` Ira Weiny
2021-11-25 11:19 ` Thomas Gleixner
2021-12-03 1:13 ` Andy Lutomirski
2021-11-25 14:12 ` Thomas Gleixner
2021-12-07 1:54 ` Ira Weiny
2021-12-07 4:45 ` Ira Weiny
2021-12-08 0:21 ` Thomas Gleixner
2021-08-04 4:32 ` [PATCH V7 09/18] x86/pks: Add PKS kernel API ira.weiny
2021-08-04 4:32 ` [PATCH V7 10/18] x86/pks: Introduce pks_abandon_protections() ira.weiny
2021-08-04 4:32 ` [PATCH V7 11/18] x86/pks: Add PKS Test code ira.weiny
2021-08-04 4:32 ` [PATCH V7 12/18] x86/pks: Add PKS fault callbacks ira.weiny
2021-08-11 21:18 ` Edgecombe, Rick P
2021-08-17 3:21 ` Ira Weiny
2021-08-04 4:32 ` [PATCH V7 13/18] memremap_pages: Add access protection via supervisor Protection Keys (PKS) ira.weiny
2021-08-04 4:32 ` [PATCH V7 14/18] memremap_pages: Add memremap.pks_fault_mode ira.weiny
2021-08-04 4:57 ` Randy Dunlap
2021-08-07 19:32 ` Ira Weiny
2021-08-11 19:01 ` Edgecombe, Rick P
2021-08-17 3:12 ` Ira Weiny
2021-08-04 4:32 ` [PATCH V7 15/18] kmap: Add stray access protection for devmap pages ira.weiny
2021-08-04 4:32 ` [PATCH V7 16/18] dax: Stray access protection for dax_direct_access() ira.weiny
2021-08-04 4:32 ` [PATCH V7 17/18] nvdimm/pmem: Enable stray access protection ira.weiny
2021-08-04 4:32 ` [PATCH V7 18/18] devdax: " ira.weiny
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