Commit c6f31932 authored by H. Peter Anvin's avatar H. Peter Anvin
Browse files

x86: msr: propagate errors from smp_call_function_single() 



Propagate error (-ENXIO) from smp_call_function_single().  These
errors can happen when a CPU is unplugged while the MSR driver is
open.

Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent f73be6de

arch/x86/kernel/msr.c

+10 −4
Original line number Diff line number Diff line
@@ -79,8 +79,11 @@ static ssize_t msr_read(struct file *file, char __user *buf, 


	for (; count; count -= 8) {

		err = rdmsr_safe_on_cpu(cpu, reg, &data[0], &data[1]);

		if (err)

			return -EIO;

		if (err) {

			if (err == -EFAULT) /* Fix idiotic error code */

				err = -EIO;

			return err;

		}

		if (copy_to_user(tmp, &data, 8))

			return -EFAULT;

		tmp += 2;
@@ -105,8 +108,11 @@ static ssize_t msr_write(struct file *file, const char __user *buf, 
		if (copy_from_user(&data, tmp, 8))

			return -EFAULT;

		err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]);

		if (err)

			return -EIO;

		if (err) {

			if (err == -EFAULT) /* Fix idiotic error code */

				err = -EIO;

			return err;

		}

		tmp += 2;

	}

arch/x86/lib/msr-on-cpu.c

+12 −10
Original line number Diff line number Diff line
@@ -30,10 +30,11 @@ static int _rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h, int safe) 


	rv.msr_no = msr_no;

	if (safe) {

		smp_call_function_single(cpu, __rdmsr_safe_on_cpu, &rv, 1);

		err = rv.err;

		err = smp_call_function_single(cpu, __rdmsr_safe_on_cpu,

					       &rv, 1);

		err = err ? err : rv.err;

	} else {

		smp_call_function_single(cpu, __rdmsr_on_cpu, &rv, 1);

		err = smp_call_function_single(cpu, __rdmsr_on_cpu, &rv, 1);

	}

	*l = rv.l;

	*h = rv.h;
@@ -64,23 +65,24 @@ static int _wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h, int safe) 
	rv.l = l;

	rv.h = h;

	if (safe) {

		smp_call_function_single(cpu, __wrmsr_safe_on_cpu, &rv, 1);

		err = rv.err;

		err = smp_call_function_single(cpu, __wrmsr_safe_on_cpu,

					       &rv, 1);

		err = err ? err : rv.err;

	} else {

		smp_call_function_single(cpu, __wrmsr_on_cpu, &rv, 1);

		err = smp_call_function_single(cpu, __wrmsr_on_cpu, &rv, 1);

	}



	return err;

}



void wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)

int wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)

{

	_wrmsr_on_cpu(cpu, msr_no, l, h, 0);

	return _wrmsr_on_cpu(cpu, msr_no, l, h, 0);

}



void rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h)

int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h)

{

	_rdmsr_on_cpu(cpu, msr_no, l, h, 0);

	return _rdmsr_on_cpu(cpu, msr_no, l, h, 0);

}



/* These "safe" variants are slower and should be used when the target MSR

include/asm-x86/msr.h

+6 −5
Original line number Diff line number Diff line
@@ -192,19 +192,20 @@ do { \ 
#define write_rdtscp_aux(val) wrmsr(0xc0000103, (val), 0)



#ifdef CONFIG_SMP

void rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h);

void wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h);

int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h);

int wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h);

int rdmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h);



int wrmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h);

#else  /*  CONFIG_SMP  */

static inline void rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h)

static inline int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h)

{

	rdmsr(msr_no, *l, *h);

	return 0;

}

static inline void wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)

static inline int wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)

{

	wrmsr(msr_no, l, h);

	return 0;

}

static inline int rdmsr_safe_on_cpu(unsigned int cpu, u32 msr_no,

				    u32 *l, u32 *h)