* [PATCH 1/4] x86/fpu/xstate: Fix __fpu_restore_sig() for XSAVES
2016-07-11 16:18 [PATCH 0/4] x86/fpu/xstate: Fix XSAVES issues - Part 3 Fenghua Yu
@ 2016-07-11 16:18 ` Fenghua Yu
2016-07-11 16:12 ` [tip:x86/fpu] " tip-bot for Yu-cheng Yu
2016-07-11 16:18 ` [PATCH 2/4] x86/fpu/xstate: Return NULL for disabled xstate component address Fenghua Yu
` (2 subsequent siblings)
3 siblings, 1 reply; 9+ messages in thread
From: Fenghua Yu @ 2016-07-11 16:18 UTC (permalink / raw)
To: Ingo Molnar, Thomas Gleixner, H. Peter Anvin, Dave Hansen,
Ravi V Shankar
Cc: Yu-cheng Yu, Fenghua Yu, x86, linux-kernel
From: Yu-cheng Yu <yu-cheng.yu@intel.com>
When the kernel is using XSAVES compacted format, we cannot do
__copy_from_user() from a signal frame, which has standard-format data.
Fix it by using copyin_to_xsaves(), which converts between formats and
filters out all supervisor states that we do not allow userspace to
write.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
---
arch/x86/kernel/fpu/signal.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index 8aa96cb..9e231d8 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -323,8 +323,15 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
*/
fpu__drop(fpu);
- if (__copy_from_user(&fpu->state.xsave, buf_fx, state_size) ||
- __copy_from_user(&env, buf, sizeof(env))) {
+ if (using_compacted_format()) {
+ err = copyin_to_xsaves(NULL, buf_fx,
+ &fpu->state.xsave);
+ } else {
+ err = __copy_from_user(&fpu->state.xsave,
+ buf_fx, state_size);
+ }
+
+ if (err || __copy_from_user(&env, buf, sizeof(env))) {
fpstate_init(&fpu->state);
trace_x86_fpu_init_state(fpu);
err = -1;
--
2.5.0
^ permalink raw reply [flat|nested] 9+ messages in thread* [tip:x86/fpu] x86/fpu/xstate: Fix __fpu_restore_sig() for XSAVES
2016-07-11 16:18 ` [PATCH 1/4] x86/fpu/xstate: Fix __fpu_restore_sig() for XSAVES Fenghua Yu
@ 2016-07-11 16:12 ` tip-bot for Yu-cheng Yu
0 siblings, 0 replies; 9+ messages in thread
From: tip-bot for Yu-cheng Yu @ 2016-07-11 16:12 UTC (permalink / raw)
To: linux-tip-commits
Cc: h.peter.anvin, mingo, torvalds, hpa, dave.hansen, yu-cheng.yu,
tglx, linux-kernel, peterz, ravi.v.shankar, fenghua.yu
Commit-ID: 1fc2b67b43d5001b92b3a002b988884ad0137e99
Gitweb: http://git.kernel.org/tip/1fc2b67b43d5001b92b3a002b988884ad0137e99
Author: Yu-cheng Yu <yu-cheng.yu@intel.com>
AuthorDate: Mon, 11 Jul 2016 09:18:54 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 11 Jul 2016 16:43:59 +0200
x86/fpu/xstate: Fix __fpu_restore_sig() for XSAVES
When the kernel is using XSAVES compacted format, we cannot do
__copy_from_user() from a signal frame, which has standard-format data.
Fix it by using copyin_to_xsaves(), which converts between formats and
filters out all supervisor states that we do not allow userspace to
write.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <h.peter.anvin@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi V Shankar <ravi.v.shankar@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1468253937-40008-2-git-send-email-fenghua.yu@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/fpu/signal.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index 8aa96cb..9e231d8 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -323,8 +323,15 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
*/
fpu__drop(fpu);
- if (__copy_from_user(&fpu->state.xsave, buf_fx, state_size) ||
- __copy_from_user(&env, buf, sizeof(env))) {
+ if (using_compacted_format()) {
+ err = copyin_to_xsaves(NULL, buf_fx,
+ &fpu->state.xsave);
+ } else {
+ err = __copy_from_user(&fpu->state.xsave,
+ buf_fx, state_size);
+ }
+
+ if (err || __copy_from_user(&env, buf, sizeof(env))) {
fpstate_init(&fpu->state);
trace_x86_fpu_init_state(fpu);
err = -1;
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH 2/4] x86/fpu/xstate: Return NULL for disabled xstate component address
2016-07-11 16:18 [PATCH 0/4] x86/fpu/xstate: Fix XSAVES issues - Part 3 Fenghua Yu
2016-07-11 16:18 ` [PATCH 1/4] x86/fpu/xstate: Fix __fpu_restore_sig() for XSAVES Fenghua Yu
@ 2016-07-11 16:18 ` Fenghua Yu
2016-07-11 16:13 ` [tip:x86/fpu] " tip-bot for Yu-cheng Yu
2016-07-11 16:18 ` [PATCH 3/4] x86/fpu/xstate: Fix fpstate_init() for XRSTORS Fenghua Yu
2016-07-11 16:18 ` [PATCH 4/4] x86/fpu/xstate: Re-enable XSAVES Fenghua Yu
3 siblings, 1 reply; 9+ messages in thread
From: Fenghua Yu @ 2016-07-11 16:18 UTC (permalink / raw)
To: Ingo Molnar, Thomas Gleixner, H. Peter Anvin, Dave Hansen,
Ravi V Shankar
Cc: Yu-cheng Yu, Fenghua Yu, x86, linux-kernel
From: Yu-cheng Yu <yu-cheng.yu@intel.com>
It is an error to request a disabled XSAVE/XSAVES component address.
For that case, make __raw_xsave_addr() return a NULL and issue a
warning.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
---
arch/x86/kernel/fpu/xstate.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index f8d1aff..4fb8dd7 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -760,6 +760,11 @@ void *__raw_xsave_addr(struct xregs_state *xsave, int xstate_feature_mask)
{
int feature_nr = fls64(xstate_feature_mask) - 1;
+ if (!xfeature_enabled(feature_nr)) {
+ WARN_ON_FPU(1);
+ return NULL;
+ }
+
return (void *)xsave + xstate_comp_offsets[feature_nr];
}
/*
--
2.5.0
^ permalink raw reply [flat|nested] 9+ messages in thread* [tip:x86/fpu] x86/fpu/xstate: Return NULL for disabled xstate component address
2016-07-11 16:18 ` [PATCH 2/4] x86/fpu/xstate: Return NULL for disabled xstate component address Fenghua Yu
@ 2016-07-11 16:13 ` tip-bot for Yu-cheng Yu
0 siblings, 0 replies; 9+ messages in thread
From: tip-bot for Yu-cheng Yu @ 2016-07-11 16:13 UTC (permalink / raw)
To: linux-tip-commits
Cc: yu-cheng.yu, h.peter.anvin, linux-kernel, tglx, hpa, torvalds,
peterz, fenghua.yu, mingo, ravi.v.shankar, dave.hansen
Commit-ID: 5060b91513b866f774da15dfd82157864c4b1683
Gitweb: http://git.kernel.org/tip/5060b91513b866f774da15dfd82157864c4b1683
Author: Yu-cheng Yu <yu-cheng.yu@intel.com>
AuthorDate: Mon, 11 Jul 2016 09:18:55 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 11 Jul 2016 16:44:00 +0200
x86/fpu/xstate: Return NULL for disabled xstate component address
It is an error to request a disabled XSAVE/XSAVES component address.
For that case, make __raw_xsave_addr() return a NULL and issue a
warning.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <h.peter.anvin@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi V Shankar <ravi.v.shankar@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1468253937-40008-3-git-send-email-fenghua.yu@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/fpu/xstate.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index f8d1aff..4fb8dd7 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -760,6 +760,11 @@ void *__raw_xsave_addr(struct xregs_state *xsave, int xstate_feature_mask)
{
int feature_nr = fls64(xstate_feature_mask) - 1;
+ if (!xfeature_enabled(feature_nr)) {
+ WARN_ON_FPU(1);
+ return NULL;
+ }
+
return (void *)xsave + xstate_comp_offsets[feature_nr];
}
/*
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH 3/4] x86/fpu/xstate: Fix fpstate_init() for XRSTORS
2016-07-11 16:18 [PATCH 0/4] x86/fpu/xstate: Fix XSAVES issues - Part 3 Fenghua Yu
2016-07-11 16:18 ` [PATCH 1/4] x86/fpu/xstate: Fix __fpu_restore_sig() for XSAVES Fenghua Yu
2016-07-11 16:18 ` [PATCH 2/4] x86/fpu/xstate: Return NULL for disabled xstate component address Fenghua Yu
@ 2016-07-11 16:18 ` Fenghua Yu
2016-07-11 16:13 ` [tip:x86/fpu] " tip-bot for Yu-cheng Yu
2016-07-11 16:18 ` [PATCH 4/4] x86/fpu/xstate: Re-enable XSAVES Fenghua Yu
3 siblings, 1 reply; 9+ messages in thread
From: Fenghua Yu @ 2016-07-11 16:18 UTC (permalink / raw)
To: Ingo Molnar, Thomas Gleixner, H. Peter Anvin, Dave Hansen,
Ravi V Shankar
Cc: Yu-cheng Yu, Fenghua Yu, x86, linux-kernel
From: Yu-cheng Yu <yu-cheng.yu@intel.com>
In XSAVES mode if fpstate_init() is used to initialize a
task's extended state area, xsave.header.xcomp_bv[63] must
be set. Otherwise, when the task is scheduled, a warning is
triggered from copy_kernel_to_xregs().
One such test case is: setting an invalid extended state
through PTRACE. When xstateregs_set() rejects the syscall
and re-initializes the task's extended state area. This triggers
the warning mentioned above.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
---
arch/x86/include/asm/fpu/types.h | 6 ++++++
arch/x86/kernel/fpu/core.c | 8 ++++++++
2 files changed, 14 insertions(+)
diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h
index 12dd648..48df486 100644
--- a/arch/x86/include/asm/fpu/types.h
+++ b/arch/x86/include/asm/fpu/types.h
@@ -232,6 +232,12 @@ struct xstate_header {
} __attribute__((packed));
/*
+ * xstate_header.xcomp_bv[63] indicates that the extended_state_area
+ * is in compacted format.
+ */
+#define XCOMP_BV_COMPACTED_FORMAT ((u64)1 << 63)
+
+/*
* This is our most modern FPU state format, as saved by the XSAVE
* and restored by the XRSTOR instructions.
*
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index c759bd0..3fc03a0 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -8,6 +8,7 @@
#include <asm/fpu/internal.h>
#include <asm/fpu/regset.h>
#include <asm/fpu/signal.h>
+#include <asm/fpu/types.h>
#include <asm/traps.h>
#include <linux/hardirq.h>
@@ -229,6 +230,13 @@ void fpstate_init(union fpregs_state *state)
memset(state, 0, fpu_kernel_xstate_size);
+ /*
+ * XRSTORS requires that this bit is set in xcomp_bv, or
+ * it will #GP. Make sure it is replaced after the memset().
+ */
+ if (static_cpu_has(X86_FEATURE_XSAVES))
+ state->xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT;
+
if (static_cpu_has(X86_FEATURE_FXSR))
fpstate_init_fxstate(&state->fxsave);
else
--
2.5.0
^ permalink raw reply [flat|nested] 9+ messages in thread* [tip:x86/fpu] x86/fpu/xstate: Fix fpstate_init() for XRSTORS
2016-07-11 16:18 ` [PATCH 3/4] x86/fpu/xstate: Fix fpstate_init() for XRSTORS Fenghua Yu
@ 2016-07-11 16:13 ` tip-bot for Yu-cheng Yu
0 siblings, 0 replies; 9+ messages in thread
From: tip-bot for Yu-cheng Yu @ 2016-07-11 16:13 UTC (permalink / raw)
To: linux-tip-commits
Cc: fenghua.yu, ravi.v.shankar, mingo, tglx, yu-cheng.yu,
linux-kernel, hpa, dave.hansen, peterz, h.peter.anvin, torvalds
Commit-ID: 35ac2d7ba787eb4b7418a5a6f5919c25e10a780a
Gitweb: http://git.kernel.org/tip/35ac2d7ba787eb4b7418a5a6f5919c25e10a780a
Author: Yu-cheng Yu <yu-cheng.yu@intel.com>
AuthorDate: Mon, 11 Jul 2016 09:18:56 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 11 Jul 2016 16:44:00 +0200
x86/fpu/xstate: Fix fpstate_init() for XRSTORS
In XSAVES mode if fpstate_init() is used to initialize a
task's extended state area, xsave.header.xcomp_bv[63] must
be set. Otherwise, when the task is scheduled, a warning is
triggered from copy_kernel_to_xregs().
One such test case is: setting an invalid extended state
through PTRACE. When xstateregs_set() rejects the syscall
and re-initializes the task's extended state area. This triggers
the warning mentioned above.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <h.peter.anvin@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi V Shankar <ravi.v.shankar@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1468253937-40008-4-git-send-email-fenghua.yu@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/include/asm/fpu/types.h | 6 ++++++
arch/x86/kernel/fpu/core.c | 8 ++++++++
2 files changed, 14 insertions(+)
diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h
index 12dd648..48df486 100644
--- a/arch/x86/include/asm/fpu/types.h
+++ b/arch/x86/include/asm/fpu/types.h
@@ -232,6 +232,12 @@ struct xstate_header {
} __attribute__((packed));
/*
+ * xstate_header.xcomp_bv[63] indicates that the extended_state_area
+ * is in compacted format.
+ */
+#define XCOMP_BV_COMPACTED_FORMAT ((u64)1 << 63)
+
+/*
* This is our most modern FPU state format, as saved by the XSAVE
* and restored by the XRSTOR instructions.
*
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index c759bd0..3fc03a0 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -8,6 +8,7 @@
#include <asm/fpu/internal.h>
#include <asm/fpu/regset.h>
#include <asm/fpu/signal.h>
+#include <asm/fpu/types.h>
#include <asm/traps.h>
#include <linux/hardirq.h>
@@ -229,6 +230,13 @@ void fpstate_init(union fpregs_state *state)
memset(state, 0, fpu_kernel_xstate_size);
+ /*
+ * XRSTORS requires that this bit is set in xcomp_bv, or
+ * it will #GP. Make sure it is replaced after the memset().
+ */
+ if (static_cpu_has(X86_FEATURE_XSAVES))
+ state->xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT;
+
if (static_cpu_has(X86_FEATURE_FXSR))
fpstate_init_fxstate(&state->fxsave);
else
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH 4/4] x86/fpu/xstate: Re-enable XSAVES
2016-07-11 16:18 [PATCH 0/4] x86/fpu/xstate: Fix XSAVES issues - Part 3 Fenghua Yu
` (2 preceding siblings ...)
2016-07-11 16:18 ` [PATCH 3/4] x86/fpu/xstate: Fix fpstate_init() for XRSTORS Fenghua Yu
@ 2016-07-11 16:18 ` Fenghua Yu
2016-07-11 16:14 ` [tip:x86/fpu] " tip-bot for Yu-cheng Yu
3 siblings, 1 reply; 9+ messages in thread
From: Fenghua Yu @ 2016-07-11 16:18 UTC (permalink / raw)
To: Ingo Molnar, Thomas Gleixner, H. Peter Anvin, Dave Hansen,
Ravi V Shankar
Cc: Yu-cheng Yu, Fenghua Yu, x86, linux-kernel
From: Yu-cheng Yu <yu-cheng.yu@intel.com>
We did not handle XSAVES instructions correctly. There were issues in
converting between standard and compacted format when interfacing with
user-space. These issues have been corrected.
Add a WARN_ONCE() to make it clear that XSAVES supervisor states are not
yet implemented.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
---
arch/x86/kernel/fpu/init.c | 15 ---------------
arch/x86/kernel/fpu/xstate.c | 9 +++++++++
2 files changed, 9 insertions(+), 15 deletions(-)
diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index 60f3839..93982ae 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -230,21 +230,6 @@ static void __init fpu__init_system_xstate_size_legacy(void)
}
fpu_user_xstate_size = fpu_kernel_xstate_size;
-
- /*
- * Quirk: we don't yet handle the XSAVES* instructions
- * correctly, as we don't correctly convert between
- * standard and compacted format when interfacing
- * with user-space - so disable it for now.
- *
- * The difference is small: with recent CPUs the
- * compacted format is only marginally smaller than
- * the standard FPU state format.
- *
- * ( This is easy to backport while we are fixing
- * XSAVES* support. )
- */
- setup_clear_cpu_cap(X86_FEATURE_XSAVES);
}
/*
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 4fb8dd7..3169bca 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -221,6 +221,15 @@ void fpu__init_cpu_xstate(void)
{
if (!boot_cpu_has(X86_FEATURE_XSAVE) || !xfeatures_mask)
return;
+ /*
+ * Make it clear that XSAVES supervisor states are not yet
+ * implemented should anyone expect it to work by changing
+ * bits in XFEATURE_MASK_* macros and XCR0.
+ */
+ WARN_ONCE((xfeatures_mask & XFEATURE_MASK_SUPERVISOR),
+ "x86/fpu: XSAVES supervisor states are not yet implemented.\n");
+
+ xfeatures_mask &= ~XFEATURE_MASK_SUPERVISOR;
cr4_set_bits(X86_CR4_OSXSAVE);
xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask);
--
2.5.0
^ permalink raw reply [flat|nested] 9+ messages in thread* [tip:x86/fpu] x86/fpu/xstate: Re-enable XSAVES
2016-07-11 16:18 ` [PATCH 4/4] x86/fpu/xstate: Re-enable XSAVES Fenghua Yu
@ 2016-07-11 16:14 ` tip-bot for Yu-cheng Yu
0 siblings, 0 replies; 9+ messages in thread
From: tip-bot for Yu-cheng Yu @ 2016-07-11 16:14 UTC (permalink / raw)
To: linux-tip-commits
Cc: yu-cheng.yu, linux-kernel, h.peter.anvin, tglx, torvalds, mingo,
dave.hansen, peterz, fenghua.yu, ravi.v.shankar, hpa
Commit-ID: b8be15d588060a03569ac85dc4a0247460988f5b
Gitweb: http://git.kernel.org/tip/b8be15d588060a03569ac85dc4a0247460988f5b
Author: Yu-cheng Yu <yu-cheng.yu@intel.com>
AuthorDate: Mon, 11 Jul 2016 09:18:57 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 11 Jul 2016 16:44:01 +0200
x86/fpu/xstate: Re-enable XSAVES
We did not handle XSAVES instructions correctly. There were issues in
converting between standard and compacted format when interfacing with
user-space. These issues have been corrected.
Add a WARN_ONCE() to make it clear that XSAVES supervisor states are not
yet implemented.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <h.peter.anvin@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi V Shankar <ravi.v.shankar@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1468253937-40008-5-git-send-email-fenghua.yu@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/fpu/init.c | 15 ---------------
arch/x86/kernel/fpu/xstate.c | 9 +++++++++
2 files changed, 9 insertions(+), 15 deletions(-)
diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index 60f3839..93982ae 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -230,21 +230,6 @@ static void __init fpu__init_system_xstate_size_legacy(void)
}
fpu_user_xstate_size = fpu_kernel_xstate_size;
-
- /*
- * Quirk: we don't yet handle the XSAVES* instructions
- * correctly, as we don't correctly convert between
- * standard and compacted format when interfacing
- * with user-space - so disable it for now.
- *
- * The difference is small: with recent CPUs the
- * compacted format is only marginally smaller than
- * the standard FPU state format.
- *
- * ( This is easy to backport while we are fixing
- * XSAVES* support. )
- */
- setup_clear_cpu_cap(X86_FEATURE_XSAVES);
}
/*
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 4fb8dd7..3169bca 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -221,6 +221,15 @@ void fpu__init_cpu_xstate(void)
{
if (!boot_cpu_has(X86_FEATURE_XSAVE) || !xfeatures_mask)
return;
+ /*
+ * Make it clear that XSAVES supervisor states are not yet
+ * implemented should anyone expect it to work by changing
+ * bits in XFEATURE_MASK_* macros and XCR0.
+ */
+ WARN_ONCE((xfeatures_mask & XFEATURE_MASK_SUPERVISOR),
+ "x86/fpu: XSAVES supervisor states are not yet implemented.\n");
+
+ xfeatures_mask &= ~XFEATURE_MASK_SUPERVISOR;
cr4_set_bits(X86_CR4_OSXSAVE);
xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask);
^ permalink raw reply [flat|nested] 9+ messages in thread