x86/mm: Only use tlb_remove_table() for paravirt

If we don't use paravirt; don't play unnecessary and complicated games
to free page-tables.

Suggested-by: Linus Torvalds <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Rik van Riel <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: Peter Zijlstra

arch/x86/Kconfig

@@ -180,7 +180,7 @@ config X86
 	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
 	select HAVE_PERF_REGS
 	select HAVE_PERF_USER_STACK_DUMP
-	select HAVE_RCU_TABLE_FREE
+	select HAVE_RCU_TABLE_FREE		if PARAVIRT
 	select HAVE_RCU_TABLE_INVALIDATE	if HAVE_RCU_TABLE_FREE
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	select HAVE_RELIABLE_STACKTRACE		if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION

arch/x86/hyperv/mmu.c

@@ -9,6 +9,7 @@
 #include <asm/mshyperv.h>
 #include <asm/msr.h>
 #include <asm/tlbflush.h>
+#include <asm/tlb.h>
 
 #define CREATE_TRACE_POINTS
 #include <asm/trace/hyperv.h>
@@ -231,4 +232,5 @@ void hyperv_setup_mmu_ops(void)
 
 	pr_info("Using hypercall for remote TLB flush\n");
 	pv_mmu_ops.flush_tlb_others = hyperv_flush_tlb_others;
+	pv_mmu_ops.tlb_remove_table = tlb_remove_table;
 }

arch/x86/include/asm/paravirt.h

@@ -309,6 +309,11 @@ static inline void flush_tlb_others(const struct cpumask *cpumask,
 	PVOP_VCALL2(pv_mmu_ops.flush_tlb_others, cpumask, info);
 }
 
+static inline void paravirt_tlb_remove_table(struct mmu_gather *tlb, void *table)
+{
+	PVOP_VCALL2(pv_mmu_ops.tlb_remove_table, tlb, table);
+}
+
 static inline int paravirt_pgd_alloc(struct mm_struct *mm)
 {
 	return PVOP_CALL1(int, pv_mmu_ops.pgd_alloc, mm);

arch/x86/include/asm/paravirt_types.h

@@ -54,6 +54,7 @@ struct desc_struct;
 struct task_struct;
 struct cpumask;
 struct flush_tlb_info;
+struct mmu_gather;
 
 /*
  * Wrapper type for pointers to code which uses the non-standard
@@ -222,6 +223,8 @@ struct pv_mmu_ops {
 	void (*flush_tlb_others)(const struct cpumask *cpus,
 				 const struct flush_tlb_info *info);
 
+	void (*tlb_remove_table)(struct mmu_gather *tlb, void *table);
+
 	/* Hooks for allocating and freeing a pagetable top-level */
 	int  (*pgd_alloc)(struct mm_struct *mm);
 	void (*pgd_free)(struct mm_struct *mm, pgd_t *pgd);

arch/x86/include/asm/tlbflush.h

@@ -552,6 +552,9 @@ extern void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch);
 #ifndef CONFIG_PARAVIRT
 #define flush_tlb_others(mask, info)	\
 	native_flush_tlb_others(mask, info)
+
+#define paravirt_tlb_remove_table(tlb, page) \
+	tlb_remove_page(tlb, (void *)(page))
 #endif
 
 #endif /* _ASM_X86_TLBFLUSH_H */

arch/x86/kernel/kvm.c

@@ -45,6 +45,7 @@
 #include <asm/apic.h>
 #include <asm/apicdef.h>
 #include <asm/hypervisor.h>
+#include <asm/tlb.h>
 
 static int kvmapf = 1;
 
@@ -636,8 +637,10 @@ static void __init kvm_guest_init(void)
 
 	if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
 	    !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
-	    kvm_para_has_feature(KVM_FEATURE_STEAL_TIME))
+	    kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
 		pv_mmu_ops.flush_tlb_others = kvm_flush_tlb_others;
+		pv_mmu_ops.tlb_remove_table = tlb_remove_table;
+	}
 
 	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
 		apic_set_eoi_write(kvm_guest_apic_eoi_write);

arch/x86/kernel/paravirt.c

@@ -41,6 +41,7 @@
 #include <asm/tlbflush.h>
 #include <asm/timer.h>
 #include <asm/special_insns.h>
+#include <asm/tlb.h>
 
 /*
  * nop stub, which must not clobber anything *including the stack* to
@@ -409,6 +410,7 @@ struct pv_mmu_ops pv_mmu_ops __ro_after_init = {
 	.flush_tlb_kernel = native_flush_tlb_global,
 	.flush_tlb_one_user = native_flush_tlb_one_user,
 	.flush_tlb_others = native_flush_tlb_others,
+	.tlb_remove_table = (void (*)(struct mmu_gather *, void *))tlb_remove_page,
 
 	.pgd_alloc = __paravirt_pgd_alloc,
 	.pgd_free = paravirt_nop,

arch/x86/mm/pgtable.c

@@ -63,7 +63,7 @@ void ___pte_free_tlb(struct mmu_gather *tlb, struct page *pte)
 {
 	pgtable_page_dtor(pte);
 	paravirt_release_pte(page_to_pfn(pte));
-	tlb_remove_table(tlb, pte);
+	paravirt_tlb_remove_table(tlb, pte);
 }
 
 #if CONFIG_PGTABLE_LEVELS > 2
@@ -79,21 +79,21 @@ void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
 	tlb->need_flush_all = 1;
 #endif
 	pgtable_pmd_page_dtor(page);
-	tlb_remove_table(tlb, page);
+	paravirt_tlb_remove_table(tlb, page);
 }
 
 #if CONFIG_PGTABLE_LEVELS > 3
 void ___pud_free_tlb(struct mmu_gather *tlb, pud_t *pud)
 {
 	paravirt_release_pud(__pa(pud) >> PAGE_SHIFT);
-	tlb_remove_table(tlb, virt_to_page(pud));
+	paravirt_tlb_remove_table(tlb, virt_to_page(pud));
 }
 
 #if CONFIG_PGTABLE_LEVELS > 4
 void ___p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d)
 {
 	paravirt_release_p4d(__pa(p4d) >> PAGE_SHIFT);
-	tlb_remove_table(tlb, virt_to_page(p4d));
+	paravirt_tlb_remove_table(tlb, virt_to_page(p4d));
 }
 #endif	/* CONFIG_PGTABLE_LEVELS > 4 */
 #endif	/* CONFIG_PGTABLE_LEVELS > 3 */

arch/x86/xen/mmu_pv.c

@@ -67,6 +67,7 @@
 #include <asm/init.h>
 #include <asm/pat.h>
 #include <asm/smp.h>
+#include <asm/tlb.h>
 
 #include <asm/xen/hypercall.h>
 #include <asm/xen/hypervisor.h>
@@ -2397,6 +2398,7 @@ static const struct pv_mmu_ops xen_mmu_ops __initconst = {
 	.flush_tlb_kernel = xen_flush_tlb,
 	.flush_tlb_one_user = xen_flush_tlb_one_user,
 	.flush_tlb_others = xen_flush_tlb_others,
+	.tlb_remove_table = tlb_remove_table,
 
 	.pgd_alloc = xen_pgd_alloc,
 	.pgd_free = xen_pgd_free,