mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-02 21:26:44 +07:00
06fc732c33
Impact: Fix race condition xen_mc_batch has a small preempt race where it takes the address of a percpu variable immediately before disabling interrupts, thereby leaving a small window in which we may migrate to another cpu and save the flags in the wrong percpu variable. Disable interrupts before saving the old flags in a percpu. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
63 lines
1.6 KiB
C
63 lines
1.6 KiB
C
#ifndef _XEN_MULTICALLS_H
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#define _XEN_MULTICALLS_H
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#include "xen-ops.h"
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/* Multicalls */
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struct multicall_space
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{
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struct multicall_entry *mc;
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void *args;
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};
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/* Allocate room for a multicall and its args */
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struct multicall_space __xen_mc_entry(size_t args);
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DECLARE_PER_CPU(unsigned long, xen_mc_irq_flags);
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/* Call to start a batch of multiple __xen_mc_entry()s. Must be
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paired with xen_mc_issue() */
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static inline void xen_mc_batch(void)
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{
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unsigned long flags;
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/* need to disable interrupts until this entry is complete */
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local_irq_save(flags);
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__get_cpu_var(xen_mc_irq_flags) = flags;
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}
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static inline struct multicall_space xen_mc_entry(size_t args)
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{
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xen_mc_batch();
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return __xen_mc_entry(args);
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}
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/* Flush all pending multicalls */
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void xen_mc_flush(void);
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/* Issue a multicall if we're not in a lazy mode */
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static inline void xen_mc_issue(unsigned mode)
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{
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if ((paravirt_get_lazy_mode() & mode) == 0)
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xen_mc_flush();
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/* restore flags saved in xen_mc_batch */
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local_irq_restore(x86_read_percpu(xen_mc_irq_flags));
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}
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/* Set up a callback to be called when the current batch is flushed */
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void xen_mc_callback(void (*fn)(void *), void *data);
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/*
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* Try to extend the arguments of the previous multicall command. The
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* previous command's op must match. If it does, then it attempts to
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* extend the argument space allocated to the multicall entry by
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* arg_size bytes.
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*
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* The returned multicall_space will return with mc pointing to the
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* command on success, or NULL on failure, and args pointing to the
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* newly allocated space.
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*/
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struct multicall_space xen_mc_extend_args(unsigned long op, size_t arg_size);
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#endif /* _XEN_MULTICALLS_H */
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