[PATCH 0/6] tip-queue 2015-11-23

[PATCH 0/6] tip-queue 2015-11-23

[Borislav Petkov]

From: Borislav Petkov <bp@suse.de>

Hi Ingo,

here's this week's queue.

"x86/microcode: Initialize the driver late when facilities are up" is
for tip-urgent as it fixes a regression which came into the 4.4 merge
window.

The rest is 4.5 stuff.

Thanks.

Borislav Petkov (6):
  x86/cpu: Unify CPU family, model, stepping calculation
  kvm: Add accessors for guest CPU's family, model, stepping
  x86/cpu/amd, kvm: Satisfy guest kernel reads of IC_CFG MSR
  x86/microcode: Initialize the driver late when facilities are up
  x86/cpu: Fix MSR value truncation issue
  x86/MSR: Chop off lower 32-bit value

[PATCH 1/6] x86/cpu: Unify CPU family, model, stepping calculation

[Borislav Petkov]

From: Borislav Petkov <bp@suse.de>

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.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
---
 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

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 <asm/cpu.h>
 #include <linux/earlycpio.h>
 
 #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 4ddd780aeac9..c311b51efe15 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -582,14 +582,9 @@ 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 <linux/module.h>
+
+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);
-- 
2.3.5

[PATCH 2/6] kvm: Add accessors for guest CPU's family, model, stepping

[Borislav Petkov]

From: Borislav Petkov <bp@suse.de>

Those give the family, model and stepping of the guest vcpu.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
---
 arch/x86/kvm/cpuid.h | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

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 <asm/cpu.h>
 
 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
-- 
2.3.5

[PATCH 3/6] x86/cpu/amd, kvm: Satisfy guest kernel reads of IC_CFG MSR

[Borislav Petkov]

From: Borislav Petkov <bp@suse.de>

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.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
---
 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(-)

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 9f3905697f12..5384485f8569 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -322,6 +322,7 @@
 #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);
 	}
-- 
2.3.5

[PATCH tip-urgent 4/6] x86/microcode: Initialize the driver late when facilities are up

[Borislav Petkov]

From: Borislav Petkov <bp@suse.de>

Running microcode_init() from setup_arch() is a bad idea because not
even kmalloc() is ready at that point and the loader does all kinds of
allocations and init/registration with various subsystems.

Make it a late initcall when required facilities are initialized so that
the microcode driver initialization can succeed too.

Reported-and-tested-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
---
 arch/x86/kernel/cpu/microcode/core.c | 1 +
 arch/x86/kernel/setup.c              | 2 --
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index 7fc27f1cca58..b3e94ef461fd 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -698,3 +698,4 @@ int __init microcode_init(void)
 	return error;
 
 }
+late_initcall(microcode_init);
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 29db25f9a745..d2bbe343fda7 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1250,8 +1250,6 @@ void __init setup_arch(char **cmdline_p)
 	if (efi_enabled(EFI_BOOT))
 		efi_apply_memmap_quirks();
 #endif
-
-	microcode_init();
 }
 
 #ifdef CONFIG_X86_32
-- 
2.3.5

[PATCH 5/6] x86/cpu: Fix MSR value truncation issue

[Borislav Petkov]

From: Borislav Petkov <bp@suse.de>

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 <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/kernel/cpu/common.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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
-- 
2.3.5

[PATCH 6/6] x86/MSR: Chop off lower 32-bit value

[Borislav Petkov]

From: Borislav Petkov <bp@suse.de>

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.

Signed-off-by: Borislav Petkov <bp@suse.de>
Suggested-by: Andy Lutomirski <luto@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/include/asm/msr.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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 */
-- 
2.3.5

[tip:x86/cpu] x86/cpu: Unify CPU family, model, stepping calculation

[tip-bot for Borislav Petkov]

Commit-ID:  99f925ce927e4ac313d9af8bd1bf55796e2cdcb1
Gitweb:     http://git.kernel.org/tip/99f925ce927e4ac313d9af8bd1bf55796e2cdcb1
Author:     Borislav Petkov <bp@suse.de>
AuthorDate: Mon, 23 Nov 2015 11:12:21 +0100
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 24 Nov 2015 09:15:54 +0100

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 <bp@suse.de>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1448273546-2567-2-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 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(-)

diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
index bf2caa1..678637a 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 34e62b1..1e1b07a 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 <asm/cpu.h>
 #include <linux/earlycpio.h>
 
 #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 c2b7522..0bed416 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 7fc27f1..3aaffb6 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 ce47402..ee81c54 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 f258788..a501fa2 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 0000000..aa417a9
--- /dev/null
+++ b/arch/x86/lib/cpu.c
@@ -0,0 +1,35 @@
+#include <linux/module.h>
+
+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);

[tip:x86/cpu] kvm: Add accessors for guest CPU's family, model, stepping

[tip-bot for Borislav Petkov]

Commit-ID:  91713faf386be6d7e6556b656436813f8c4ee552
Gitweb:     http://git.kernel.org/tip/91713faf386be6d7e6556b656436813f8c4ee552
Author:     Borislav Petkov <bp@suse.de>
AuthorDate: Mon, 23 Nov 2015 11:12:22 +0100
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 24 Nov 2015 09:15:54 +0100

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 <bp@suse.de>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1448273546-2567-3-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kvm/cpuid.h | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index 06332cb..5d47e0d 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 <asm/cpu.h>
 
 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

[tip:x86/cpu] x86/cpu/amd, kvm: Satisfy guest kernel reads of IC_CFG MSR

[tip-bot for Borislav Petkov]

Commit-ID:  ae8b787543d872cf89a7f9ef8aa302f3ef9bcbd7
Gitweb:     http://git.kernel.org/tip/ae8b787543d872cf89a7f9ef8aa302f3ef9bcbd7
Author:     Borislav Petkov <bp@suse.de>
AuthorDate: Mon, 23 Nov 2015 11:12:23 +0100
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 24 Nov 2015 09:15:54 +0100

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 <bp@suse.de>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1448273546-2567-4-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 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(-)

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 690b402..b05402e 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 a8816b3..e229640 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 83a1c64..58b64c1 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);
 	}

[tip:x86/cpu] x86/cpu: Fix MSR value truncation issue

[tip-bot for Borislav Petkov]

Commit-ID:  31ac34ca5636e596485c6e03df1879643bde585e
Gitweb:     http://git.kernel.org/tip/31ac34ca5636e596485c6e03df1879643bde585e
Author:     Borislav Petkov <bp@suse.de>
AuthorDate: Mon, 23 Nov 2015 11:12:25 +0100
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 24 Nov 2015 09:15:55 +0100

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 <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1448273546-2567-6-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/cpu/common.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 0bed416..105da8d 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

[tip:x86/cpu] x86/MSR: Chop off lower 32-bit value

[tip-bot for Borislav Petkov]

Commit-ID:  679bcea857d72868e3431dde3a0e158bf0ed9119
Gitweb:     http://git.kernel.org/tip/679bcea857d72868e3431dde3a0e158bf0ed9119
Author:     Borislav Petkov <bp@suse.de>
AuthorDate: Mon, 23 Nov 2015 11:12:26 +0100
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 24 Nov 2015 09:15:55 +0100

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 <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1448273546-2567-7-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/msr.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
index 77d8b28..8613382 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 */