forked from KolibriOS/kolibrios
92 lines
1.4 KiB
C
92 lines
1.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/preempt.h>
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#include <asm/msr.h>
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/**
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* Read an MSR with error handling
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*
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* @msr: MSR to read
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* @m: value to read into
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*
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* It returns read data only on success, otherwise it doesn't change the output
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* argument @m.
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*
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*/
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int msr_read(u32 msr, struct msr *m)
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{
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int err;
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u64 val;
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err = rdmsrl_safe(msr, &val);
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if (!err)
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m->q = val;
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return err;
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}
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/**
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* Write an MSR with error handling
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*
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* @msr: MSR to write
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* @m: value to write
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*/
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int msr_write(u32 msr, struct msr *m)
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{
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return wrmsrl_safe(msr, m->q);
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}
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static inline int __flip_bit(u32 msr, u8 bit, bool set)
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{
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struct msr m, m1;
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int err = -EINVAL;
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if (bit > 63)
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return err;
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err = msr_read(msr, &m);
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if (err)
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return err;
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m1 = m;
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if (set)
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m1.q |= BIT_64(bit);
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else
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m1.q &= ~BIT_64(bit);
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if (m1.q == m.q)
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return 0;
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err = msr_write(msr, &m1);
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if (err)
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return err;
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return 1;
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}
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/**
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* Set @bit in a MSR @msr.
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*
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* Retval:
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* < 0: An error was encountered.
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* = 0: Bit was already set.
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* > 0: Hardware accepted the MSR write.
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*/
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int msr_set_bit(u32 msr, u8 bit)
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{
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return __flip_bit(msr, bit, true);
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}
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/**
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* Clear @bit in a MSR @msr.
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*
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* Retval:
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* < 0: An error was encountered.
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* = 0: Bit was already cleared.
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* > 0: Hardware accepted the MSR write.
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*/
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int msr_clear_bit(u32 msr, u8 bit)
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{
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return __flip_bit(msr, bit, false);
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}
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