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x86/xen: Get rid of last XEN_LAZY_MMU uses

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There are only very few use cases of XEN_LAZY_MMU left. Get rid of
them in order to avoid having to call enter_lazy(XEN_LAZY_MMU) and
leave_lazy(XEN_LAZY_MMU).

The query in xen_batched_set_pte() can be replaced by using
is_lazy_mmu_mode_active() instead.

As xen_flush_lazy_mmu() will be called only with lazy MMU mode being
active, the test for the lazy mode can just be dropped.

In xen_start_context_switch() and xen_end_context_switch() use
__task_lazy_mmu_mode_pause() and __task_lazy_mmu_mode_resume(),
allowing to drop xen_enter_lazy_mmu() and xen_leave_lazy_mmu()
completely.

Call arch_flush_lazy_mmu_mode() from arch_leave_lazy_mmu_mode(), as
this is the only required action now.

Drop the lazy mmu enter and leave paravirt hooks, leaving the flush
hook as the only needed one.

Signed-off-by: Juergen Gross <jgross@suse.com>
Message-ID: <20260526150514.129330-5-jgross@suse.com>
This commit is contained in:
Juergen Gross 2026-05-26 17:05:13 +02:00
parent 811f0d8caa
commit bec6f41a6f
5 changed files with 13 additions and 52 deletions
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13
arch/x86/include/asm/paravirt.h
View File

@ -483,17 +483,16 @@ static inline void arch_end_context_switch(struct task_struct *next)
static inline void arch_enter_lazy_mmu_mode(void)
{
PVOP_VCALL0(pv_ops, mmu.lazy_mode.enter);
}
static inline void arch_leave_lazy_mmu_mode(void)
{
PVOP_VCALL0(pv_ops, mmu.lazy_mode.leave);
}
static inline void arch_flush_lazy_mmu_mode(void)
{
PVOP_VCALL0(pv_ops, mmu.lazy_mode.flush);
PVOP_VCALL0(pv_ops, mmu.lazy_mode_flush);
}
static inline void arch_leave_lazy_mmu_mode(void)
{
arch_flush_lazy_mmu_mode();
}
static inline void __set_fixmap(unsigned /* enum fixed_addresses */ idx,

11
arch/x86/include/asm/paravirt_types.h
View File

@ -19,15 +19,6 @@ struct cpumask;
struct flush_tlb_info;
struct vm_area_struct;
#ifdef CONFIG_PARAVIRT_XXL
struct pv_lazy_ops {
/* Set deferred update mode, used for batching operations. */
void (*enter)(void);
void (*leave)(void);
void (*flush)(void);
} __no_randomize_layout;
#endif
struct pv_cpu_ops {
/* hooks for various privileged instructions */
#ifdef CONFIG_PARAVIRT_XXL
@ -171,7 +162,7 @@ struct pv_mmu_ops {
void (*set_pgd)(pgd_t *pgdp, pgd_t pgdval);
struct pv_lazy_ops lazy_mode;
void (*lazy_mode_flush)(void);
/* dom0 ops */

6
arch/x86/kernel/paravirt.c
View File

@ -204,11 +204,7 @@ struct paravirt_patch_template pv_ops = {
.mmu.enter_mmap = paravirt_nop,
.mmu.lazy_mode = {
.enter = paravirt_nop,
.leave = paravirt_nop,
.flush = paravirt_nop,
},
.mmu.lazy_mode_flush = paravirt_nop,
.mmu.set_fixmap = native_set_fixmap,
#endif /* CONFIG_PARAVIRT_XXL */

7
arch/x86/xen/enlighten_pv.c
View File

@ -424,9 +424,7 @@ static void xen_start_context_switch(struct task_struct *prev)
{
BUG_ON(preemptible());
if (this_cpu_read(xen_lazy_mode) == XEN_LAZY_MMU) {
arch_leave_lazy_mmu_mode();
}
__task_lazy_mmu_mode_pause(prev);
enter_lazy(XEN_LAZY_CPU);
}
@ -436,8 +434,7 @@ static void xen_end_context_switch(struct task_struct *next)
xen_mc_flush();
leave_lazy(XEN_LAZY_CPU);
if (__task_lazy_mmu_mode_active(next))
arch_enter_lazy_mmu_mode();
__task_lazy_mmu_mode_resume(next);
}
static unsigned long xen_store_tr(void)

28
arch/x86/xen/mmu_pv.c
View File

@ -324,7 +324,7 @@ static bool xen_batched_set_pte(pte_t *ptep, pte_t pteval)
{
struct mmu_update u;
if (xen_get_lazy_mode() != XEN_LAZY_MMU)
if (!is_lazy_mmu_mode_active())
return false;
xen_mc_batch();
@ -2151,21 +2151,10 @@ static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot)
#endif
}
static void xen_enter_lazy_mmu(void)
{
preempt_disable();
if (xen_get_lazy_mode() != XEN_LAZY_MMU)
enter_lazy(XEN_LAZY_MMU);
preempt_enable();
}
static void xen_flush_lazy_mmu(void)
{
preempt_disable();
if (xen_get_lazy_mode() == XEN_LAZY_MMU)
xen_mc_flush();
xen_mc_flush();
preempt_enable();
}
@ -2189,15 +2178,6 @@ static void __init xen_post_allocator_init(void)
pv_ops.mmu.write_cr3 = &xen_write_cr3;
}
static void xen_leave_lazy_mmu(void)
{
preempt_disable();
xen_mc_flush();
if (xen_get_lazy_mode() != XEN_LAZY_NONE)
leave_lazy(XEN_LAZY_MMU);
preempt_enable();
}
void __init xen_init_mmu_ops(void)
{
x86_init.paging.pagetable_init = xen_pagetable_init;
@ -2237,9 +2217,7 @@ void __init xen_init_mmu_ops(void)
pv_ops.mmu.make_p4d = PV_CALLEE_SAVE(xen_make_p4d);
pv_ops.mmu.enter_mmap = xen_enter_mmap;
pv_ops.mmu.exit_mmap = xen_exit_mmap;
pv_ops.mmu.lazy_mode.enter = xen_enter_lazy_mmu;
pv_ops.mmu.lazy_mode.leave = xen_leave_lazy_mmu;
pv_ops.mmu.lazy_mode.flush = xen_flush_lazy_mmu;
pv_ops.mmu.lazy_mode_flush = xen_flush_lazy_mmu;
pv_ops.mmu.set_fixmap = xen_set_fixmap;
memset(dummy_mapping, 0xff, PAGE_SIZE);