From 99f925ce927e4ac313d9af8bd1bf55796e2cdcb1 Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Mon, 23 Nov 2015 11:12:21 +0100 Subject: x86/cpu: Unify CPU family, model, stepping calculation Add generic functions which calc family, model and stepping from the CPUID_1.EAX leaf and stick them into the library we have. Rename those which do call CPUID with the prefix "x86_cpuid" as suggested by Paolo Bonzini. No functionality change. Signed-off-by: Borislav Petkov Reviewed-by: Paolo Bonzini Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1448273546-2567-2-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/include/asm/cpu.h | 3 +++ arch/x86/include/asm/microcode.h | 39 +++++++---------------------------- arch/x86/kernel/cpu/common.c | 11 +++------- arch/x86/kernel/cpu/microcode/core.c | 12 +++++------ arch/x86/kernel/cpu/microcode/intel.c | 16 ++++++-------- arch/x86/lib/Makefile | 2 +- arch/x86/lib/cpu.c | 35 +++++++++++++++++++++++++++++++ 7 files changed, 61 insertions(+), 57 deletions(-) create mode 100644 arch/x86/lib/cpu.c (limited to 'arch/x86') diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h index bf2caa1dedc5..678637ad7476 100644 --- a/arch/x86/include/asm/cpu.h +++ b/arch/x86/include/asm/cpu.h @@ -36,4 +36,7 @@ extern int _debug_hotplug_cpu(int cpu, int action); int mwait_usable(const struct cpuinfo_x86 *); +unsigned int x86_family(unsigned int sig); +unsigned int x86_model(unsigned int sig); +unsigned int x86_stepping(unsigned int sig); #endif /* _ASM_X86_CPU_H */ diff --git a/arch/x86/include/asm/microcode.h b/arch/x86/include/asm/microcode.h index 34e62b1dcfce..1e1b07a5a738 100644 --- a/arch/x86/include/asm/microcode.h +++ b/arch/x86/include/asm/microcode.h @@ -1,6 +1,7 @@ #ifndef _ASM_X86_MICROCODE_H #define _ASM_X86_MICROCODE_H +#include #include #define native_rdmsr(msr, val1, val2) \ @@ -95,14 +96,14 @@ static inline void __exit exit_amd_microcode(void) {} /* * In early loading microcode phase on BSP, boot_cpu_data is not set up yet. - * x86_vendor() gets vendor id for BSP. + * x86_cpuid_vendor() gets vendor id for BSP. * * In 32 bit AP case, accessing boot_cpu_data needs linear address. To simplify - * coding, we still use x86_vendor() to get vendor id for AP. + * coding, we still use x86_cpuid_vendor() to get vendor id for AP. * - * x86_vendor() gets vendor information directly from CPUID. + * x86_cpuid_vendor() gets vendor information directly from CPUID. */ -static inline int x86_vendor(void) +static inline int x86_cpuid_vendor(void) { u32 eax = 0x00000000; u32 ebx, ecx = 0, edx; @@ -118,40 +119,14 @@ static inline int x86_vendor(void) return X86_VENDOR_UNKNOWN; } -static inline unsigned int __x86_family(unsigned int sig) -{ - unsigned int x86; - - x86 = (sig >> 8) & 0xf; - - if (x86 == 0xf) - x86 += (sig >> 20) & 0xff; - - return x86; -} - -static inline unsigned int x86_family(void) +static inline unsigned int x86_cpuid_family(void) { u32 eax = 0x00000001; u32 ebx, ecx = 0, edx; native_cpuid(&eax, &ebx, &ecx, &edx); - return __x86_family(eax); -} - -static inline unsigned int x86_model(unsigned int sig) -{ - unsigned int x86, model; - - x86 = __x86_family(sig); - - model = (sig >> 4) & 0xf; - - if (x86 == 0x6 || x86 == 0xf) - model += ((sig >> 16) & 0xf) << 4; - - return model; + return x86_family(eax); } #ifdef CONFIG_MICROCODE diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index c2b7522cbf35..0bed416f8c40 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -581,14 +581,9 @@ void cpu_detect(struct cpuinfo_x86 *c) u32 junk, tfms, cap0, misc; cpuid(0x00000001, &tfms, &misc, &junk, &cap0); - c->x86 = (tfms >> 8) & 0xf; - c->x86_model = (tfms >> 4) & 0xf; - c->x86_mask = tfms & 0xf; - - if (c->x86 == 0xf) - c->x86 += (tfms >> 20) & 0xff; - if (c->x86 >= 0x6) - c->x86_model += ((tfms >> 16) & 0xf) << 4; + c->x86 = x86_family(tfms); + c->x86_model = x86_model(tfms); + c->x86_mask = x86_stepping(tfms); if (cap0 & (1<<19)) { c->x86_clflush_size = ((misc >> 8) & 0xff) * 8; diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c index 7fc27f1cca58..3aaffb601c91 100644 --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -129,8 +129,8 @@ void __init load_ucode_bsp(void) if (!have_cpuid_p()) return; - vendor = x86_vendor(); - family = x86_family(); + vendor = x86_cpuid_vendor(); + family = x86_cpuid_family(); switch (vendor) { case X86_VENDOR_INTEL: @@ -165,8 +165,8 @@ void load_ucode_ap(void) if (!have_cpuid_p()) return; - vendor = x86_vendor(); - family = x86_family(); + vendor = x86_cpuid_vendor(); + family = x86_cpuid_family(); switch (vendor) { case X86_VENDOR_INTEL: @@ -206,8 +206,8 @@ void reload_early_microcode(void) { int vendor, family; - vendor = x86_vendor(); - family = x86_family(); + vendor = x86_cpuid_vendor(); + family = x86_cpuid_family(); switch (vendor) { case X86_VENDOR_INTEL: diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c index ce47402eb2f9..ee81c544ee0d 100644 --- a/arch/x86/kernel/cpu/microcode/intel.c +++ b/arch/x86/kernel/cpu/microcode/intel.c @@ -145,10 +145,10 @@ matching_model_microcode(struct microcode_header_intel *mc_header, int ext_sigcount, i; struct extended_signature *ext_sig; - fam = __x86_family(sig); + fam = x86_family(sig); model = x86_model(sig); - fam_ucode = __x86_family(mc_header->sig); + fam_ucode = x86_family(mc_header->sig); model_ucode = x86_model(mc_header->sig); if (fam == fam_ucode && model == model_ucode) @@ -163,7 +163,7 @@ matching_model_microcode(struct microcode_header_intel *mc_header, ext_sigcount = ext_header->count; for (i = 0; i < ext_sigcount; i++) { - fam_ucode = __x86_family(ext_sig->sig); + fam_ucode = x86_family(ext_sig->sig); model_ucode = x86_model(ext_sig->sig); if (fam == fam_ucode && model == model_ucode) @@ -365,7 +365,7 @@ static int collect_cpu_info_early(struct ucode_cpu_info *uci) native_cpuid(&eax, &ebx, &ecx, &edx); csig.sig = eax; - family = __x86_family(csig.sig); + family = x86_family(csig.sig); model = x86_model(csig.sig); if ((model >= 5) || (family > 6)) { @@ -521,16 +521,12 @@ static bool __init load_builtin_intel_microcode(struct cpio_data *cp) { #ifdef CONFIG_X86_64 unsigned int eax = 0x00000001, ebx, ecx = 0, edx; - unsigned int family, model, stepping; char name[30]; native_cpuid(&eax, &ebx, &ecx, &edx); - family = __x86_family(eax); - model = x86_model(eax); - stepping = eax & 0xf; - - sprintf(name, "intel-ucode/%02x-%02x-%02x", family, model, stepping); + sprintf(name, "intel-ucode/%02x-%02x-%02x", + x86_family(eax), x86_model(eax), x86_stepping(eax)); return get_builtin_firmware(cp, name); #else diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile index f2587888d987..a501fa25da41 100644 --- a/arch/x86/lib/Makefile +++ b/arch/x86/lib/Makefile @@ -16,7 +16,7 @@ clean-files := inat-tables.c obj-$(CONFIG_SMP) += msr-smp.o cache-smp.o -lib-y := delay.o misc.o cmdline.o +lib-y := delay.o misc.o cmdline.o cpu.o lib-y += usercopy_$(BITS).o usercopy.o getuser.o putuser.o lib-y += memcpy_$(BITS).o lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o diff --git a/arch/x86/lib/cpu.c b/arch/x86/lib/cpu.c new file mode 100644 index 000000000000..aa417a97511c --- /dev/null +++ b/arch/x86/lib/cpu.c @@ -0,0 +1,35 @@ +#include + +unsigned int x86_family(unsigned int sig) +{ + unsigned int x86; + + x86 = (sig >> 8) & 0xf; + + if (x86 == 0xf) + x86 += (sig >> 20) & 0xff; + + return x86; +} +EXPORT_SYMBOL_GPL(x86_family); + +unsigned int x86_model(unsigned int sig) +{ + unsigned int fam, model; + + fam = x86_family(sig); + + model = (sig >> 4) & 0xf; + + if (fam >= 0x6) + model += ((sig >> 16) & 0xf) << 4; + + return model; +} +EXPORT_SYMBOL_GPL(x86_model); + +unsigned int x86_stepping(unsigned int sig) +{ + return sig & 0xf; +} +EXPORT_SYMBOL_GPL(x86_stepping); -- cgit v1.2.3-58-ga151 From 91713faf386be6d7e6556b656436813f8c4ee552 Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Mon, 23 Nov 2015 11:12:22 +0100 Subject: kvm: Add accessors for guest CPU's family, model, stepping Those give the family, model and stepping of the guest vcpu. Signed-off-by: Borislav Petkov Reviewed-by: Paolo Bonzini Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1448273546-2567-3-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/kvm/cpuid.h | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) (limited to 'arch/x86') diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h index 06332cb7e7d1..5d47e0d95ef1 100644 --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -2,6 +2,7 @@ #define ARCH_X86_KVM_CPUID_H #include "x86.h" +#include int kvm_update_cpuid(struct kvm_vcpu *vcpu); struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu, @@ -170,4 +171,37 @@ static inline bool guest_cpuid_has_nrips(struct kvm_vcpu *vcpu) } #undef BIT_NRIPS +static inline int guest_cpuid_family(struct kvm_vcpu *vcpu) +{ + struct kvm_cpuid_entry2 *best; + + best = kvm_find_cpuid_entry(vcpu, 0x1, 0); + if (!best) + return -1; + + return x86_family(best->eax); +} + +static inline int guest_cpuid_model(struct kvm_vcpu *vcpu) +{ + struct kvm_cpuid_entry2 *best; + + best = kvm_find_cpuid_entry(vcpu, 0x1, 0); + if (!best) + return -1; + + return x86_model(best->eax); +} + +static inline int guest_cpuid_stepping(struct kvm_vcpu *vcpu) +{ + struct kvm_cpuid_entry2 *best; + + best = kvm_find_cpuid_entry(vcpu, 0x1, 0); + if (!best) + return -1; + + return x86_stepping(best->eax); +} + #endif -- cgit v1.2.3-58-ga151 From ae8b787543d872cf89a7f9ef8aa302f3ef9bcbd7 Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Mon, 23 Nov 2015 11:12:23 +0100 Subject: x86/cpu/amd, kvm: Satisfy guest kernel reads of IC_CFG MSR The kernel accesses IC_CFG MSR (0xc0011021) on AMD because it checks whether the way access filter is enabled on some F15h models, and, if so, disables it. kvm doesn't handle that MSR access and complains about it, which can get really noisy in dmesg when one starts kvm guests all the time for testing. And it is useless anyway - guest kernel shouldn't be doing such changes anyway so tell it that that filter is disabled. Signed-off-by: Borislav Petkov Reviewed-by: Paolo Bonzini Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1448273546-2567-4-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/include/asm/msr-index.h | 1 + arch/x86/kernel/cpu/amd.c | 4 ++-- arch/x86/kvm/svm.c | 17 +++++++++++++++++ 3 files changed, 20 insertions(+), 2 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h index 690b4027e17c..b05402ef3b84 100644 --- a/arch/x86/include/asm/msr-index.h +++ b/arch/x86/include/asm/msr-index.h @@ -321,6 +321,7 @@ #define MSR_F15H_PERF_CTR 0xc0010201 #define MSR_F15H_NB_PERF_CTL 0xc0010240 #define MSR_F15H_NB_PERF_CTR 0xc0010241 +#define MSR_F15H_IC_CFG 0xc0011021 /* Fam 10h MSRs */ #define MSR_FAM10H_MMIO_CONF_BASE 0xc0010058 diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index a8816b325162..e229640c19ab 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -678,9 +678,9 @@ static void init_amd_bd(struct cpuinfo_x86 *c) * Disable it on the affected CPUs. */ if ((c->x86_model >= 0x02) && (c->x86_model < 0x20)) { - if (!rdmsrl_safe(0xc0011021, &value) && !(value & 0x1E)) { + if (!rdmsrl_safe(MSR_F15H_IC_CFG, &value) && !(value & 0x1E)) { value |= 0x1E; - wrmsrl_safe(0xc0011021, value); + wrmsrl_safe(MSR_F15H_IC_CFG, value); } } } diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 83a1c643f9a5..58b64c17c4a8 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -3053,6 +3053,23 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) case MSR_IA32_UCODE_REV: msr_info->data = 0x01000065; break; + case MSR_F15H_IC_CFG: { + + int family, model; + + family = guest_cpuid_family(vcpu); + model = guest_cpuid_model(vcpu); + + if (family < 0 || model < 0) + return kvm_get_msr_common(vcpu, msr_info); + + msr_info->data = 0; + + if (family == 0x15 && + (model >= 0x2 && model < 0x20)) + msr_info->data = 0x1E; + } + break; default: return kvm_get_msr_common(vcpu, msr_info); } -- cgit v1.2.3-58-ga151 From 31ac34ca5636e596485c6e03df1879643bde585e Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Mon, 23 Nov 2015 11:12:25 +0100 Subject: x86/cpu: Fix MSR value truncation issue So sparse rightfully complains that the u64 MSR value we're writing into the STAR MSR, i.e. 0xc0000081, is being truncated: ./arch/x86/include/asm/msr.h:193:36: warning: cast truncates bits from constant value (23001000000000 becomes 0) because the actual value doesn't fit into the unsigned 32-bit quantity which are the @low and @high wrmsrl() parameters. This is not a problem, practically, because gcc is actually being smart enough here and does the right thing: .loc 3 87 0 xorl %esi, %esi # we needz a 32-bit zero movl $2293776, %edx # 0x00230010 == (__USER32_CS << 16) | __KERNEL_CS go into the high bits movl $-1073741695, %ecx # MSR_STAR, i.e., 0xc0000081 movl %esi, %eax # low order 32 bits in the MSR which are 0 #APP # 87 "./arch/x86/include/asm/msr.h" 1 wrmsr More specifically, MSR_STAR[31:0] is being set to 0. That field is reserved on Intel and on AMD it is 32-bit SYSCALL Target EIP. I'd strongly guess because Intel doesn't have SYSCALL in compat/legacy mode and we're using SYSENTER and INT80 there. And for compat syscalls in long mode we use CSTAR. So let's fix the sparse warning by writing SYSRET and SYSCALL CS and SS into the high 32-bit half of STAR and 0 in the low half explicitly. [ Actually, if we had to be precise, we would have to read what's in STAR[31:0] and write it back unchanged on Intel and write 0 on AMD. I guess the current writing to 0 is still ok since Intel can apparently stomach it. ] The resulting code is identical to what we have above: .loc 3 87 0 xorl %esi, %esi # tmp104 movl $2293776, %eax #, tmp103 movl $-1073741695, %ecx #, tmp102 movl %esi, %edx # tmp104, tmp104 ... wrmsr Signed-off-by: Borislav Petkov Cc: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1448273546-2567-6-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86') diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 0bed416f8c40..105da8df87ae 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1180,7 +1180,7 @@ void syscall_init(void) * They both write to the same internal register. STAR allows to * set CS/DS but only a 32bit target. LSTAR sets the 64bit rip. */ - wrmsrl(MSR_STAR, ((u64)__USER32_CS)<<48 | ((u64)__KERNEL_CS)<<32); + wrmsr(MSR_STAR, 0, (__USER32_CS << 16) | __KERNEL_CS); wrmsrl(MSR_LSTAR, (unsigned long)entry_SYSCALL_64); #ifdef CONFIG_IA32_EMULATION -- cgit v1.2.3-58-ga151 From 679bcea857d72868e3431dde3a0e158bf0ed9119 Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Mon, 23 Nov 2015 11:12:26 +0100 Subject: x86/MSR: Chop off lower 32-bit value sparse complains that the cast truncates the high bits. But here we really do know what we're doing and we need the lower 32 bits only as the @low argument. So make that explicit. Suggested-by: Andy Lutomirski Signed-off-by: Borislav Petkov Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1448273546-2567-7-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/include/asm/msr.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86') diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h index 77d8b284e4a7..86133827c75c 100644 --- a/arch/x86/include/asm/msr.h +++ b/arch/x86/include/asm/msr.h @@ -190,7 +190,7 @@ static inline void wrmsr(unsigned msr, unsigned low, unsigned high) static inline void wrmsrl(unsigned msr, u64 val) { - native_write_msr(msr, (u32)val, (u32)(val >> 32)); + native_write_msr(msr, (u32)(val & 0xffffffffULL), (u32)(val >> 32)); } /* wrmsr with exception handling */ -- cgit v1.2.3-58-ga151 From 0007bccc3cfd1e69deb0fd73ccc426b4cedb061d Mon Sep 17 00:00:00 2001 From: Len Brown Date: Sun, 16 Aug 2015 11:20:00 -0400 Subject: x86: Replace RDRAND forced-reseed with simple sanity check x86_init_rdrand() was added with 2 goals: 1. Sanity check that the built-in-self-test circuit on the Digital Random Number Generator (DRNG) is not complaining. As RDRAND HW self-checks on every invocation, this goal is achieved by simply invoking RDRAND and checking its return code. 2. Force a full re-seed of the random number generator. This was done out of paranoia to benefit the most un-sophisticated DRNG implementation conceivable in the architecture, an implementation that does not exist, and unlikely ever will. This worst-case full-re-seed is achieved by invoking a 64-bit RDRAND 8192 times. Unfortunately, this worst-case re-seed costs O(1,000us). Magnifying this cost, it is done from identify_cpu(), which is the synchronous critical path to bring a processor on-line -- repeated for every logical processor in the system at boot and resume from S3. As it is very expensive, and of highly dubious value, we delete the worst-case re-seed from the kernel. We keep the 1st goal -- sanity check the hardware, and mark it absent if it complains. This change reduces the cost of x86_init_rdrand() by a factor of 1,000x, to O(1us) from O(1,000us). Signed-off-by: Len Brown Link: http://lkml.kernel.org/r/058618cc56ec6611171427ad7205e37e377aa8d4.1439738240.git.len.brown@intel.com Signed-off-by: Thomas Gleixner --- arch/x86/kernel/cpu/rdrand.c | 25 ++++++++++++------------- 1 file changed, 12 insertions(+), 13 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/kernel/cpu/rdrand.c b/arch/x86/kernel/cpu/rdrand.c index 136ac74dee82..819d94982e07 100644 --- a/arch/x86/kernel/cpu/rdrand.c +++ b/arch/x86/kernel/cpu/rdrand.c @@ -33,28 +33,27 @@ static int __init x86_rdrand_setup(char *s) __setup("nordrand", x86_rdrand_setup); /* - * Force a reseed cycle; we are architecturally guaranteed a reseed - * after no more than 512 128-bit chunks of random data. This also - * acts as a test of the CPU capability. + * RDRAND has Built-In-Self-Test (BIST) that runs on every invocation. + * Run the instruction a few times as a sanity check. + * If it fails, it is simple to disable RDRAND here. */ -#define RESEED_LOOP ((512*128)/sizeof(unsigned long)) +#define SANITY_CHECK_LOOPS 8 void x86_init_rdrand(struct cpuinfo_x86 *c) { #ifdef CONFIG_ARCH_RANDOM unsigned long tmp; - int i, count, ok; + int i; if (!cpu_has(c, X86_FEATURE_RDRAND)) - return; /* Nothing to do */ + return; - for (count = i = 0; i < RESEED_LOOP; i++) { - ok = rdrand_long(&tmp); - if (ok) - count++; + for (i = 0; i < SANITY_CHECK_LOOPS; i++) { + if (!rdrand_long(&tmp)) { + clear_cpu_cap(c, X86_FEATURE_RDRAND); + printk_once(KERN_WARNING "rdrand: disabled\n"); + return; + } } - - if (count != RESEED_LOOP) - clear_cpu_cap(c, X86_FEATURE_RDRAND); #endif } -- cgit v1.2.3-58-ga151