[V4,1/6] x86/hvm: pkeys, add the flag to enable Memory Protection Keys

Commit Message

Huaitong Han Dec. 21, 2015, 7:21 a.m. UTC

This patch adds the flag to enable Memory Protection Keys.

Signed-off-by: Huaitong Han <[e-mail]>
Reviewed-by: Andrew Cooper <[e-mail]>
---
 docs/misc/xen-command-line.markdown | 10 ++++++++++
 xen/arch/x86/cpu/common.c           | 10 +++++++++-
 xen/include/asm-x86/cpufeature.h    |  6 +++++-
 3 files changed, 24 insertions(+), 2 deletions(-)

Comments

Jan Beulich Dec. 21, 2015, 12:58 p.m. UTC | #1

>>> On 21.12.15 at 08:21, <[e-mail]> wrote:

First of all - please trim your Cc lists. I don't see, for example, why all
the tools maintainers needed to be Cc-ed on this patch.

> --- a/xen/arch/x86/cpu/common.c
> +++ b/xen/arch/x86/cpu/common.c
> @@ -22,6 +22,10 @@ boolean_param("xsave", use_xsave);
>  bool_t opt_arat = 1;
>  boolean_param("arat", opt_arat);
>  
> +/* pku: Flag to enable Memory Protection Keys (default on). */
> +bool_t opt_pku = 1;

I would have thought that I had commented on this wanting to be
static already, but looks like I'm misremembering.

Jan

Patch

diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-command-line.markdown
index c103894..36ecf80 100644
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -1177,6 +1177,16 @@  This option can be specified more than once (up to 8 times at present).
 ### ple\_window
 > `= <integer>`
 
+### pku
+> `= <boolean>`
+
+> Default: `true`
+
+Flag to enable Memory Protection Keys.
+
+The protection-key feature provides an additional mechanism by which IA-32e
+paging controls access to usermode addresses.
+
 ### psr (Intel)
 > `= List of ( cmt:<boolean> | rmid_max:<integer> | cat:<boolean> | cos_max:<integer> | cdp:<boolean> )`
 
diff --git a/xen/arch/x86/cpu/common.c b/xen/arch/x86/cpu/common.c
index 310ec85..7d03e52 100644
--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -22,6 +22,10 @@  boolean_param("xsave", use_xsave);
 bool_t opt_arat = 1;
 boolean_param("arat", opt_arat);
 
+/* pku: Flag to enable Memory Protection Keys (default on). */
+bool_t opt_pku = 1;
+boolean_param("pku", opt_pku);
+
 unsigned int opt_cpuid_mask_ecx = ~0u;
 integer_param("cpuid_mask_ecx", opt_cpuid_mask_ecx);
 unsigned int opt_cpuid_mask_edx = ~0u;
@@ -270,7 +274,8 @@  static void __cpuinit generic_identify(struct cpuinfo_x86 *c)
 	if ( c->cpuid_level >= 0x00000007 )
 		cpuid_count(0x00000007, 0, &tmp,
 			    &c->x86_capability[cpufeat_word(X86_FEATURE_FSGSBASE)],
-			    &tmp, &tmp);
+			    &c->x86_capability[cpufeat_word(X86_FEATURE_PKU)],
+			    &tmp);
 }
 
 /*
@@ -323,6 +328,9 @@  void __cpuinit identify_cpu(struct cpuinfo_x86 *c)
 	if ( cpu_has_xsave )
 		xstate_init(c);
 
+   	if ( !opt_pku )
+		setup_clear_cpu_cap(X86_FEATURE_PKU);
+
 	/*
 	 * The vendor-specific functions might have changed features.  Now
 	 * we do "generic changes."
diff --git a/xen/include/asm-x86/cpufeature.h b/xen/include/asm-x86/cpufeature.h
index af127cf..ef96514 100644
--- a/xen/include/asm-x86/cpufeature.h
+++ b/xen/include/asm-x86/cpufeature.h
@@ -11,7 +11,7 @@ 
 
 #include <xen/const.h>
 
-#define NCAPINTS	8	/* N 32-bit words worth of info */
+#define NCAPINTS	9	/* N 32-bit words worth of info */
 
 /* Intel-defined CPU features, CPUID level 0x00000001 (edx), word 0 */
 #define X86_FEATURE_FPU		(0*32+ 0) /* Onboard FPU */
@@ -163,6 +163,10 @@ 
 #define X86_FEATURE_ADX		(7*32+19) /* ADCX, ADOX instructions */
 #define X86_FEATURE_SMAP	(7*32+20) /* Supervisor Mode Access Prevention */
 
+/* Intel-defined CPU features, CPUID level 0x00000007:0 (ecx), word 8 */
+#define X86_FEATURE_PKU	(8*32+ 3) /* Protection Keys for Userspace */
+#define X86_FEATURE_OSPKE	(8*32+ 4) /* OS Protection Keys Enable */
+
 #define cpufeat_word(idx)	((idx) / 32)
 #define cpufeat_bit(idx)	((idx) % 32)
 #define cpufeat_mask(idx)	(_AC(1, U) << cpufeat_bit(idx))