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authorBorislav Petkov <bp@suse.de>2014-03-09 21:05:23 +0400
committerH. Peter Anvin <hpa@linux.intel.com>2014-03-14 02:34:45 +0400
commit22085a66c2fab6cf9b9393c056a3600a6b4735de (patch)
tree3175ffd60c8d06bc2c719ee8a27442bb5a6aed7f
parent2a0788dc9bc46789ec98aea0f30c6fb420196b12 (diff)
downloadlinux-22085a66c2fab6cf9b9393c056a3600a6b4735de.tar.xz
x86: Add another set of MSR accessor functions
We very often need to set or clear a bit in an MSR as a result of doing some sort of a hardware configuration. Add generic versions of that repeated functionality in order to save us a bunch of duplicated code in the early CPU vendor detection/config code. Signed-off-by: Borislav Petkov <bp@suse.de> Link: http://lkml.kernel.org/r/1394384725-10796-2-git-send-email-bp@alien8.de Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
-rw-r--r--arch/x86/include/asm/msr.h2
-rw-r--r--arch/x86/lib/msr.c89
2 files changed, 90 insertions, 1 deletions
diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
index e139b13f2a33..de36f22eb0b9 100644
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -214,6 +214,8 @@ do { \
struct msr *msrs_alloc(void);
void msrs_free(struct msr *msrs);
+int msr_set_bit(u32 msr, u8 bit);
+int msr_clear_bit(u32 msr, u8 bit);
#ifdef CONFIG_SMP
int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h);
diff --git a/arch/x86/lib/msr.c b/arch/x86/lib/msr.c
index 8f8eebdca7d4..db9db446b71a 100644
--- a/arch/x86/lib/msr.c
+++ b/arch/x86/lib/msr.c
@@ -8,7 +8,7 @@ struct msr *msrs_alloc(void)
msrs = alloc_percpu(struct msr);
if (!msrs) {
- pr_warning("%s: error allocating msrs\n", __func__);
+ pr_warn("%s: error allocating msrs\n", __func__);
return NULL;
}
@@ -21,3 +21,90 @@ void msrs_free(struct msr *msrs)
free_percpu(msrs);
}
EXPORT_SYMBOL(msrs_free);
+
+/**
+ * Read an MSR with error handling
+ *
+ * @msr: MSR to read
+ * @m: value to read into
+ *
+ * It returns read data only on success, otherwise it doesn't change the output
+ * argument @m.
+ *
+ */
+int msr_read(u32 msr, struct msr *m)
+{
+ int err;
+ u64 val;
+
+ err = rdmsrl_safe(msr, &val);
+ if (!err)
+ m->q = val;
+
+ return err;
+}
+
+/**
+ * Write an MSR with error handling
+ *
+ * @msr: MSR to write
+ * @m: value to write
+ */
+int msr_write(u32 msr, struct msr *m)
+{
+ return wrmsrl_safe(msr, m->q);
+}
+
+static inline int __flip_bit(u32 msr, u8 bit, bool set)
+{
+ struct msr m, m1;
+ int err = -EINVAL;
+
+ if (bit > 63)
+ return err;
+
+ err = msr_read(msr, &m);
+ if (err)
+ return err;
+
+ m1 = m;
+ if (set)
+ m1.q |= BIT_64(bit);
+ else
+ m1.q &= ~BIT_64(bit);
+
+ if (m1.q == m.q)
+ return 0;
+
+ err = msr_write(msr, &m);
+ if (err)
+ return err;
+
+ return 1;
+}
+
+/**
+ * Set @bit in a MSR @msr.
+ *
+ * Retval:
+ * < 0: An error was encountered.
+ * = 0: Bit was already set.
+ * > 0: Hardware accepted the MSR write.
+ */
+int msr_set_bit(u32 msr, u8 bit)
+{
+ return __flip_bit(msr, bit, true);
+}
+
+/**
+ * Clear @bit in a MSR @msr.
+ *
+ * Retval:
+ * < 0: An error was encountered.
+ * = 0: Bit was already cleared.
+ * > 0: Hardware accepted the MSR write.
+ */
+int msr_clear_bit(u32 msr, u8 bit)
+{
+ return __flip_bit(msr, bit, false);
+}