From 54d346e5de4cb838cff6f3b2697311efd75a6f99 Mon Sep 17 00:00:00 2001 From: Andrew Cooper Date: Thu, 24 Mar 2016 16:05:37 +0100 Subject: [PATCH] x86: mask out unknown features from Xen's capabilities If Xen doesn't know about a feature, it is unsafe for use and should be deliberately hidden from Xen's capabilities. This doesn't make a practical difference yet, but will make a difference later when the guest featuresets are seeded from the host featureset. Signed-off-by: Andrew Cooper Acked-by: Jan Beulich Reviewed-by: Konrad Rzeszutek Wilk --- xen/arch/x86/Makefile | 1 + xen/arch/x86/cpu/common.c | 2 ++ xen/arch/x86/cpuid.c | 20 ++++++++++++++++++++ xen/include/asm-x86/cpufeature.h | 4 +--- xen/include/asm-x86/cpuid.h | 25 +++++++++++++++++++++++++ xen/tools/gen-cpuid.py | 24 ++++++++++++++++++++++++ 6 files changed, 73 insertions(+), 3 deletions(-) create mode 100644 xen/arch/x86/cpuid.c create mode 100644 xen/include/asm-x86/cpuid.h diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile index 1bcb08b462..729065b660 100644 --- a/xen/arch/x86/Makefile +++ b/xen/arch/x86/Makefile @@ -12,6 +12,7 @@ obj-y += bitops.o obj-bin-y += bzimage.init.o obj-bin-y += clear_page.o obj-bin-y += copy_page.o +obj-y += cpuid.o obj-y += compat.o x86_64/compat.o obj-$(CONFIG_KEXEC) += crash.o obj-y += debug.o diff --git a/xen/arch/x86/cpu/common.c b/xen/arch/x86/cpu/common.c index 1a278b146e..d302272a4e 100644 --- a/xen/arch/x86/cpu/common.c +++ b/xen/arch/x86/cpu/common.c @@ -341,6 +341,8 @@ void identify_cpu(struct cpuinfo_x86 *c) * The vendor-specific functions might have changed features. Now * we do "generic changes." */ + for (i = 0; i < FSCAPINTS; ++i) + c->x86_capability[i] &= known_features[i]; for (i = 0 ; i < NCAPINTS ; ++i) c->x86_capability[i] &= ~cleared_caps[i]; diff --git a/xen/arch/x86/cpuid.c b/xen/arch/x86/cpuid.c new file mode 100644 index 0000000000..05cd646397 --- /dev/null +++ b/xen/arch/x86/cpuid.c @@ -0,0 +1,20 @@ +#include +#include +#include + +const uint32_t known_features[] = INIT_KNOWN_FEATURES; + +static void __init __maybe_unused build_assertions(void) +{ + BUILD_BUG_ON(ARRAY_SIZE(known_features) != FSCAPINTS); +} + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * tab-width: 4 + * indent-tabs-mode: nil + * End: + */ diff --git a/xen/include/asm-x86/cpufeature.h b/xen/include/asm-x86/cpufeature.h index bcda09bd9d..e29b024bcc 100644 --- a/xen/include/asm-x86/cpufeature.h +++ b/xen/include/asm-x86/cpufeature.h @@ -10,10 +10,8 @@ #endif #include -#include -#include +#include -#define FSCAPINTS FEATURESET_NR_ENTRIES #define NCAPINTS (FSCAPINTS + 1) /* N 32-bit words worth of info */ /* Other features, Xen-defined mapping. */ diff --git a/xen/include/asm-x86/cpuid.h b/xen/include/asm-x86/cpuid.h new file mode 100644 index 0000000000..b72d88f971 --- /dev/null +++ b/xen/include/asm-x86/cpuid.h @@ -0,0 +1,25 @@ +#ifndef __X86_CPUID_H__ +#define __X86_CPUID_H__ + +#include +#include + +#define FSCAPINTS FEATURESET_NR_ENTRIES + +#ifndef __ASSEMBLY__ +#include + +extern const uint32_t known_features[FSCAPINTS]; + +#endif /* __ASSEMBLY__ */ +#endif /* !__X86_CPUID_H__ */ + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * tab-width: 4 + * indent-tabs-mode: nil + * End: + */ diff --git a/xen/tools/gen-cpuid.py b/xen/tools/gen-cpuid.py index c6bd98d850..ae337e3b9e 100755 --- a/xen/tools/gen-cpuid.py +++ b/xen/tools/gen-cpuid.py @@ -19,6 +19,8 @@ class State(object): # State calculated self.nr_entries = 0 # Number of words in a featureset + self.common_1d = 0 # Common features between 1d and e1d + self.known = [] # All known features def parse_definitions(state): """ @@ -95,6 +97,22 @@ def crunch_numbers(state): # Size of bitmaps state.nr_entries = nr_entries = (max(state.names.keys()) >> 5) + 1 + # Features common between 1d and e1d. + common_1d = (FPU, VME, DE, PSE, TSC, MSR, PAE, MCE, CX8, APIC, + MTRR, PGE, MCA, CMOV, PAT, PSE36, MMX, FXSR) + + # All known features. Duplicate the common features in e1d + e1d_base = SYSCALL & ~31 + state.known = featureset_to_uint32s( + state.names.keys() + [ e1d_base + (x % 32) for x in common_1d ], + nr_entries) + + # Fold common back into names + for f in common_1d: + state.names[e1d_base + (f % 32)] = "E1D_" + state.names[f] + + state.common_1d = featureset_to_uint32s(common_1d, 1)[0] + def write_results(state): state.output.write( @@ -109,7 +127,13 @@ def write_results(state): state.output.write( """ #define FEATURESET_NR_ENTRIES %sU + +#define CPUID_COMMON_1D_FEATURES %s + +#define INIT_KNOWN_FEATURES { \\\n%s\n} """ % (state.nr_entries, + state.common_1d, + format_uint32s(state.known, 4), )) state.output.write( -- 2.30.2