[PATCHv3 1/7] x86/boot: Detect 5-level paging support

From: Kirill A. Shutemov
Date: Thu Mar 30 2017 - 04:09:16 EST


5-level paging support is required from hardware when compiled with
CONFIG_X86_5LEVEL=y.

We will implement boot-time switch between 4- and 5-level paging later.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
arch/x86/boot/cpucheck.c | 9 +++++++++
arch/x86/boot/cpuflags.c | 12 ++++++++++--
arch/x86/include/asm/disabled-features.h | 8 +++++++-
arch/x86/include/asm/required-features.h | 8 +++++++-
4 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/arch/x86/boot/cpucheck.c b/arch/x86/boot/cpucheck.c
index 4ad7d70e8739..8f0c4c9fc904 100644
--- a/arch/x86/boot/cpucheck.c
+++ b/arch/x86/boot/cpucheck.c
@@ -44,6 +44,15 @@ static const u32 req_flags[NCAPINTS] =
0, /* REQUIRED_MASK5 not implemented in this file */
REQUIRED_MASK6,
0, /* REQUIRED_MASK7 not implemented in this file */
+ 0, /* REQUIRED_MASK8 not implemented in this file */
+ 0, /* REQUIRED_MASK9 not implemented in this file */
+ 0, /* REQUIRED_MASK10 not implemented in this file */
+ 0, /* REQUIRED_MASK11 not implemented in this file */
+ 0, /* REQUIRED_MASK12 not implemented in this file */
+ 0, /* REQUIRED_MASK13 not implemented in this file */
+ 0, /* REQUIRED_MASK14 not implemented in this file */
+ 0, /* REQUIRED_MASK15 not implemented in this file */
+ REQUIRED_MASK16,
};

#define A32(a, b, c, d) (((d) << 24)+((c) << 16)+((b) << 8)+(a))
diff --git a/arch/x86/boot/cpuflags.c b/arch/x86/boot/cpuflags.c
index 6687ab953257..9e77c23c2422 100644
--- a/arch/x86/boot/cpuflags.c
+++ b/arch/x86/boot/cpuflags.c
@@ -70,16 +70,19 @@ int has_eflag(unsigned long mask)
# define EBX_REG "=b"
#endif

-static inline void cpuid(u32 id, u32 *a, u32 *b, u32 *c, u32 *d)
+static inline void cpuid_count(u32 id, u32 count,
+ u32 *a, u32 *b, u32 *c, u32 *d)
{
asm volatile(".ifnc %%ebx,%3 ; movl %%ebx,%3 ; .endif \n\t"
"cpuid \n\t"
".ifnc %%ebx,%3 ; xchgl %%ebx,%3 ; .endif \n\t"
: "=a" (*a), "=c" (*c), "=d" (*d), EBX_REG (*b)
- : "a" (id)
+ : "a" (id), "c" (count)
);
}

+#define cpuid(id, a, b, c, d) cpuid_count(id, 0, a, b, c, d)
+
void get_cpuflags(void)
{
u32 max_intel_level, max_amd_level;
@@ -108,6 +111,11 @@ void get_cpuflags(void)
cpu.model += ((tfms >> 16) & 0xf) << 4;
}

+ if (max_intel_level >= 0x00000007) {
+ cpuid_count(0x00000007, 0, &ignored, &ignored,
+ &cpu.flags[16], &ignored);
+ }
+
cpuid(0x80000000, &max_amd_level, &ignored, &ignored,
&ignored);

diff --git a/arch/x86/include/asm/disabled-features.h b/arch/x86/include/asm/disabled-features.h
index 85599ad4d024..5dff775af7cd 100644
--- a/arch/x86/include/asm/disabled-features.h
+++ b/arch/x86/include/asm/disabled-features.h
@@ -36,6 +36,12 @@
# define DISABLE_OSPKE (1<<(X86_FEATURE_OSPKE & 31))
#endif /* CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS */

+#ifdef CONFIG_X86_5LEVEL
+# define DISABLE_LA57 0
+#else
+# define DISABLE_LA57 (1<<(X86_FEATURE_LA57 & 31))
+#endif
+
/*
* Make sure to add features to the correct mask
*/
@@ -55,7 +61,7 @@
#define DISABLED_MASK13 0
#define DISABLED_MASK14 0
#define DISABLED_MASK15 0
-#define DISABLED_MASK16 (DISABLE_PKU|DISABLE_OSPKE)
+#define DISABLED_MASK16 (DISABLE_PKU|DISABLE_OSPKE|DISABLE_LA57)
#define DISABLED_MASK17 0
#define DISABLED_MASK_CHECK BUILD_BUG_ON_ZERO(NCAPINTS != 18)

diff --git a/arch/x86/include/asm/required-features.h b/arch/x86/include/asm/required-features.h
index fac9a5c0abe9..d91ba04dd007 100644
--- a/arch/x86/include/asm/required-features.h
+++ b/arch/x86/include/asm/required-features.h
@@ -53,6 +53,12 @@
# define NEED_MOVBE 0
#endif

+#ifdef CONFIG_X86_5LEVEL
+# define NEED_LA57 (1<<(X86_FEATURE_LA57 & 31))
+#else
+# define NEED_LA57 0
+#endif
+
#ifdef CONFIG_X86_64
#ifdef CONFIG_PARAVIRT
/* Paravirtualized systems may not have PSE or PGE available */
@@ -98,7 +104,7 @@
#define REQUIRED_MASK13 0
#define REQUIRED_MASK14 0
#define REQUIRED_MASK15 0
-#define REQUIRED_MASK16 0
+#define REQUIRED_MASK16 (NEED_LA57)
#define REQUIRED_MASK17 0
#define REQUIRED_MASK_CHECK BUILD_BUG_ON_ZERO(NCAPINTS != 18)

--
2.11.0