| 0,0 → 1,91 |
|---|
| // SPDX-License-Identifier: GPL-2.0 |
| |
| #include <linux/preempt.h> |
| #include <asm/msr.h> |
| |
| /** |
| * 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, &m1); |
| 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); |
| } |