[tip:x86/fpu] x86/fpu/xstate: Re-enable XSAVES

2016-07-11 Thread tip-bot for Yu-cheng Yu 
Commit-ID:  b8be15d588060a03569ac85dc4a0247460988f5b
Gitweb: http://git.kernel.org/tip/b8be15d588060a03569ac85dc4a0247460988f5b
Author: Yu-cheng Yu 
AuthorDate: Mon, 11 Jul 2016 09:18:57 -0700
Committer:  Ingo Molnar 
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 
Signed-off-by: Fenghua Yu 
Reviewed-by: Dave Hansen 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Ravi V Shankar 
Cc: Thomas Gleixner 
Link: 
http://lkml.kernel.org/r/1468253937-40008-5-git-send-email-fenghua...@intel.com
Signed-off-by: Ingo Molnar 
---
 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);

[tip:x86/fpu] x86/fpu/xstate: Re-enable XSAVES

2016-07-11 Thread tip-bot for Yu-cheng Yu 
Commit-ID:  b8be15d588060a03569ac85dc4a0247460988f5b
Gitweb: http://git.kernel.org/tip/b8be15d588060a03569ac85dc4a0247460988f5b
Author: Yu-cheng Yu 
AuthorDate: Mon, 11 Jul 2016 09:18:57 -0700
Committer:  Ingo Molnar 
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 
Signed-off-by: Fenghua Yu 
Reviewed-by: Dave Hansen 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Ravi V Shankar 
Cc: Thomas Gleixner 
Link: 
http://lkml.kernel.org/r/1468253937-40008-5-git-send-email-fenghua...@intel.com
Signed-off-by: Ingo Molnar 
---
 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);