400d34944c
Some Xen hypercalls accept an array of operations to work on. In general this is because its more efficient for the hypercall to the work all at once rather than as separate hypercalls (even batched as a multicall). This patch adds a mechanism (xen_mc_extend_args()) to allocate more argument space to the last-issued multicall, in order to extend its argument list. The user of this mechanism is xen/mmu.c, which uses it to extend the args array of mmu_update. This is particularly valuable when doing the update for a large mprotect, which goes via ptep_modify_prot_commit(), but it also manages to batch updates to pgd/pmds as well. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
60 lines
1.6 KiB
C
60 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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/* need to disable interrupts until this entry is complete */
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local_irq_save(__get_cpu_var(xen_mc_irq_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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