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powerpc/mm: Rename find_linux_pte_or_hugepte()

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Add newer helpers to make the function usage simpler. It is always
recommended to use find_current_mm_pte() for walking the page table.
If we cannot use find_current_mm_pte(), it should be documented why
the said usage of __find_linux_pte() is safe against a parallel THP
split.

For now we have KVM code using __find_linux_pte(). This is because kvm
code ends up calling __find_linux_pte() in real mode with MSR_EE=0 but
with PACA soft_enabled = 1. We may want to fix that later and make
sure we keep the MSR_EE and PACA soft_enabled in sync. When we do that
we can switch kvm to use find_linux_pte().

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Aneesh Kumar K.V 2017-07-27 11:54:53 +05:30 committed by Michael Ellerman
parent 520eccdfe1
commit 94171b19c3
13 changed files with 103 additions and 55 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
arch/powerpc/include/asm/pgtable.h
View File

@ -66,16 +66,8 @@ extern int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
#ifndef CONFIG_TRANSPARENT_HUGEPAGE
#define pmd_large(pmd) 0
#endif
pte_t *__find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea,
bool *is_thp, unsigned *shift);
static inline pte_t *find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea,
bool *is_thp, unsigned *shift)
{
VM_WARN(!arch_irqs_disabled(),
"%s called with irq enabled\n", __func__);
return __find_linux_pte_or_hugepte(pgdir, ea, is_thp, shift);
}
/* can we use this in kvm */
unsigned long vmalloc_to_phys(void *vmalloc_addr);
void pgtable_cache_add(unsigned shift, void (*ctor)(void *));

35
arch/powerpc/include/asm/pte-walk.h Normal file
View File

@ -0,0 +1,35 @@
#ifndef _ASM_POWERPC_PTE_WALK_H
#define _ASM_POWERPC_PTE_WALK_H
#include <linux/sched.h>
/* Don't use this directly */
extern pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
bool *is_thp, unsigned *hshift);
static inline pte_t *find_linux_pte(pgd_t *pgdir, unsigned long ea,
bool *is_thp, unsigned *hshift)
{
VM_WARN(!arch_irqs_disabled(), "%s called with irq enabled\n", __func__);
return __find_linux_pte(pgdir, ea, is_thp, hshift);
}
static inline pte_t *find_init_mm_pte(unsigned long ea, unsigned *hshift)
{
pgd_t *pgdir = init_mm.pgd;
return __find_linux_pte(pgdir, ea, NULL, hshift);
}
/*
* This is what we should always use. Any other lockless page table lookup needs
* careful audit against THP split.
*/
static inline pte_t *find_current_mm_pte(pgd_t *pgdir, unsigned long ea,
bool *is_thp, unsigned *hshift)
{
VM_WARN(!arch_irqs_disabled(), "%s called with irq enabled\n", __func__);
VM_WARN(pgdir != current->mm->pgd,
"%s lock less page table lookup called on wrong mm\n", __func__);
return __find_linux_pte(pgdir, ea, is_thp, hshift);
}
#endif /* _ASM_POWERPC_PTE_WALK_H */

4
arch/powerpc/kernel/eeh.c
View File

@ -44,6 +44,7 @@
#include <asm/machdep.h>
#include <asm/ppc-pci.h>
#include <asm/rtas.h>
#include <asm/pte-walk.h>
/** Overview:
@ -352,8 +353,7 @@ static inline unsigned long eeh_token_to_phys(unsigned long token)
* worried about _PAGE_SPLITTING/collapse. Also we will not hit
* page table free, because of init_mm.
*/
ptep = __find_linux_pte_or_hugepte(init_mm.pgd, token,
NULL, &hugepage_shift);
ptep = find_init_mm_pte(token, &hugepage_shift);
if (!ptep)
return token;
WARN_ON(hugepage_shift);

5
arch/powerpc/kernel/io-workarounds.c
View File

@ -19,6 +19,8 @@
#include <asm/pgtable.h>
#include <asm/ppc-pci.h>
#include <asm/io-workarounds.h>
#include <asm/pte-walk.h>
#define IOWA_MAX_BUS 8
@ -75,8 +77,7 @@ struct iowa_bus *iowa_mem_find_bus(const PCI_IO_ADDR addr)
* We won't find huge pages here (iomem). Also can't hit
* a page table free due to init_mm
*/
ptep = __find_linux_pte_or_hugepte(init_mm.pgd, vaddr,
NULL, &hugepage_shift);
ptep = find_init_mm_pte(vaddr, &hugepage_shift);
if (ptep == NULL)
paddr = 0;
else {

5
arch/powerpc/kvm/book3s_64_mmu_hv.c
View File

@ -37,6 +37,7 @@
#include <asm/synch.h>
#include <asm/ppc-opcode.h>
#include <asm/cputable.h>
#include <asm/pte-walk.h>
#include "trace_hv.h"
@ -597,8 +598,8 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
* hugepage split and collapse.
*/
local_irq_save(flags);
ptep = find_linux_pte_or_hugepte(current->mm->pgd,
hva, NULL, NULL);
ptep = find_current_mm_pte(current->mm->pgd,
hva, NULL, NULL);
if (ptep) {
pte = kvmppc_read_update_linux_pte(ptep, 1);
if (__pte_write(pte))

28
arch/powerpc/kvm/book3s_64_mmu_radix.c
View File

@ -17,6 +17,7 @@
#include <asm/mmu.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/pte-walk.h>
/*
* Supported radix tree geometry.
@ -359,8 +360,7 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
if (writing)
pgflags |= _PAGE_DIRTY;
local_irq_save(flags);
ptep = __find_linux_pte_or_hugepte(current->mm->pgd, hva,
NULL, NULL);
ptep = find_current_mm_pte(current->mm->pgd, hva, NULL, NULL);
if (ptep) {
pte = READ_ONCE(*ptep);
if (pte_present(pte) &&
@ -374,8 +374,12 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
spin_unlock(&kvm->mmu_lock);
return RESUME_GUEST;
}
ptep = __find_linux_pte_or_hugepte(kvm->arch.pgtable,
gpa, NULL, &shift);
/*
* We are walking the secondary page table here. We can do this
* without disabling irq.
*/
ptep = __find_linux_pte(kvm->arch.pgtable,
gpa, NULL, &shift);
if (ptep && pte_present(*ptep)) {
kvmppc_radix_update_pte(kvm, ptep, 0, pgflags,
gpa, shift);
@ -427,8 +431,8 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
pgflags |= _PAGE_WRITE;
} else {
local_irq_save(flags);
ptep = __find_linux_pte_or_hugepte(current->mm->pgd,
hva, NULL, NULL);
ptep = find_current_mm_pte(current->mm->pgd,
hva, NULL, NULL);
if (ptep && pte_write(*ptep) && pte_dirty(*ptep))
pgflags |= _PAGE_WRITE;
local_irq_restore(flags);
@ -499,8 +503,7 @@ int kvm_unmap_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
unsigned int shift;
unsigned long old;
ptep = __find_linux_pte_or_hugepte(kvm->arch.pgtable, gpa,
NULL, &shift);
ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
if (ptep && pte_present(*ptep)) {
old = kvmppc_radix_update_pte(kvm, ptep, _PAGE_PRESENT, 0,
gpa, shift);
@ -525,8 +528,7 @@ int kvm_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
unsigned int shift;
int ref = 0;
ptep = __find_linux_pte_or_hugepte(kvm->arch.pgtable, gpa,
NULL, &shift);
ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
if (ptep && pte_present(*ptep) && pte_young(*ptep)) {
kvmppc_radix_update_pte(kvm, ptep, _PAGE_ACCESSED, 0,
gpa, shift);
@ -545,8 +547,7 @@ int kvm_test_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
unsigned int shift;
int ref = 0;
ptep = __find_linux_pte_or_hugepte(kvm->arch.pgtable, gpa,
NULL, &shift);
ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
if (ptep && pte_present(*ptep) && pte_young(*ptep))
ref = 1;
return ref;
@ -562,8 +563,7 @@ static int kvm_radix_test_clear_dirty(struct kvm *kvm,
unsigned int shift;
int ret = 0;
ptep = __find_linux_pte_or_hugepte(kvm->arch.pgtable, gpa,
NULL, &shift);
ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
if (ptep && pte_present(*ptep) && pte_dirty(*ptep)) {
ret = 1;
if (shift)

12
arch/powerpc/kvm/book3s_64_vio_hv.c
View File

@ -39,6 +39,7 @@
#include <asm/udbg.h>
#include <asm/iommu.h>
#include <asm/tce.h>
#include <asm/pte-walk.h>
#ifdef CONFIG_BUG
@ -353,7 +354,16 @@ static long kvmppc_rm_ua_to_hpa(struct kvm_vcpu *vcpu,
pte_t *ptep, pte;
unsigned shift = 0;
ptep = __find_linux_pte_or_hugepte(vcpu->arch.pgdir, ua, NULL, &shift);
/*
* Called in real mode with MSR_EE = 0. We are safe here.
* It is ok to do the lookup with arch.pgdir here, because
* we are doing this on secondary cpus and current task there
* is not the hypervisor. Also this is safe against THP in the
* host, because an IPI to primary thread will wait for the secondary
* to exit which will agains result in the below page table walk
* to finish.
*/
ptep = __find_linux_pte(vcpu->arch.pgdir, ua, NULL, &shift);
if (!ptep || !pte_present(*ptep))
return -ENXIO;
pte = *ptep;

18
arch/powerpc/kvm/book3s_hv_rm_mmu.c
View File

@ -22,6 +22,7 @@
#include <asm/hvcall.h>
#include <asm/synch.h>
#include <asm/ppc-opcode.h>
#include <asm/pte-walk.h>
/* Translate address of a vmalloc'd thing to a linear map address */
static void *real_vmalloc_addr(void *x)
@ -31,9 +32,9 @@ static void *real_vmalloc_addr(void *x)
/*
* assume we don't have huge pages in vmalloc space...
* So don't worry about THP collapse/split. Called
* Only in realmode, hence won't need irq_save/restore.
* Only in realmode with MSR_EE = 0, hence won't need irq_save/restore.
*/
p = __find_linux_pte_or_hugepte(swapper_pg_dir, addr, NULL, NULL);
p = find_init_mm_pte(addr, NULL);
if (!p || !pte_present(*p))
return NULL;
addr = (pte_pfn(*p) << PAGE_SHIFT) | (addr & ~PAGE_MASK);
@ -230,14 +231,13 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
* If we had a page table table change after lookup, we would
* retry via mmu_notifier_retry.
*/
if (realmode)
ptep = __find_linux_pte_or_hugepte(pgdir, hva, NULL,
&hpage_shift);
else {
if (!realmode)
local_irq_save(irq_flags);
ptep = find_linux_pte_or_hugepte(pgdir, hva, NULL,
&hpage_shift);
}
/*
* If called in real mode we have MSR_EE = 0. Otherwise
* we disable irq above.
*/
ptep = __find_linux_pte(pgdir, hva, NULL, &hpage_shift);
if (ptep) {
pte_t pte;
unsigned int host_pte_size;

3
arch/powerpc/kvm/e500_mmu_host.c
View File

@ -30,6 +30,7 @@
#include <linux/vmalloc.h>
#include <linux/hugetlb.h>
#include <asm/kvm_ppc.h>
#include <asm/pte-walk.h>
#include "e500.h"
#include "timing.h"
@ -476,7 +477,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
* can't run hence pfn won't change.
*/
local_irq_save(flags);
ptep = find_linux_pte_or_hugepte(pgdir, hva, NULL, NULL);
ptep = find_linux_pte(pgdir, hva, NULL, NULL);
if (ptep) {
pte_t pte = READ_ONCE(*ptep);

5
arch/powerpc/mm/hash_utils_64.c
View File

@ -61,6 +61,7 @@
#include <asm/tm.h>
#include <asm/trace.h>
#include <asm/ps3.h>
#include <asm/pte-walk.h>
#ifdef DEBUG
#define DBG(fmt...) udbg_printf(fmt)
@ -1297,7 +1298,7 @@ int hash_page_mm(struct mm_struct *mm, unsigned long ea,
#endif /* CONFIG_PPC_64K_PAGES */
/* Get PTE and page size from page tables */
ptep = __find_linux_pte_or_hugepte(pgdir, ea, &is_thp, &hugeshift);
ptep = find_linux_pte(pgdir, ea, &is_thp, &hugeshift);
if (ptep == NULL || !pte_present(*ptep)) {
DBG_LOW(" no PTE !\n");
rc = 1;
@ -1526,7 +1527,7 @@ void hash_preload(struct mm_struct *mm, unsigned long ea,
* THP pages use update_mmu_cache_pmd. We don't do
* hash preload there. Hence can ignore THP here
*/
ptep = find_linux_pte_or_hugepte(pgdir, ea, NULL, &hugepage_shift);
ptep = find_current_mm_pte(pgdir, ea, NULL, &hugepage_shift);
if (!ptep)
goto out_exit;

24
arch/powerpc/mm/hugetlbpage.c
View File

@ -24,6 +24,8 @@
#include <asm/tlb.h>
#include <asm/setup.h>
#include <asm/hugetlb.h>
#include <asm/pte-walk.h>
#ifdef CONFIG_HUGETLB_PAGE
@ -60,8 +62,11 @@ static unsigned nr_gpages;
pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr, unsigned long sz)
{
/* Only called for hugetlbfs pages, hence can ignore THP */
return __find_linux_pte_or_hugepte(mm->pgd, addr, NULL, NULL);
/*
* Only called for hugetlbfs pages, hence can ignore THP and the
* irq disabled walk.
*/
return __find_linux_pte(mm->pgd, addr, NULL, NULL);
}
static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
@ -886,9 +891,8 @@ void flush_dcache_icache_hugepage(struct page *page)
* This function need to be called with interrupts disabled. We use this variant
* when we have MSR[EE] = 0 but the paca->soft_enabled = 1
*/
pte_t *__find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea,
bool *is_thp, unsigned *shift)
pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
bool *is_thp, unsigned *hpage_shift)
{
pgd_t pgd, *pgdp;
pud_t pud, *pudp;
@ -897,8 +901,8 @@ pte_t *__find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea,
hugepd_t *hpdp = NULL;
unsigned pdshift = PGDIR_SHIFT;
if (shift)
*shift = 0;
if (hpage_shift)
*hpage_shift = 0;
if (is_thp)
*is_thp = false;
@ -968,11 +972,11 @@ pte_t *__find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea,
ret_pte = hugepte_offset(*hpdp, ea, pdshift);
pdshift = hugepd_shift(*hpdp);
out:
if (shift)
*shift = pdshift;
if (hpage_shift)
*hpage_shift = pdshift;
return ret_pte;
}
EXPORT_SYMBOL_GPL(__find_linux_pte_or_hugepte);
EXPORT_SYMBOL_GPL(__find_linux_pte);
int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
unsigned long end, int write, struct page **pages, int *nr)

6
arch/powerpc/mm/tlb_hash64.c
View File

@ -29,6 +29,8 @@
#include <asm/tlbflush.h>
#include <asm/tlb.h>
#include <asm/bug.h>
#include <asm/pte-walk.h>
#include <trace/events/thp.h>
@ -207,8 +209,8 @@ void __flush_hash_table_range(struct mm_struct *mm, unsigned long start,
local_irq_save(flags);
arch_enter_lazy_mmu_mode();
for (; start < end; start += PAGE_SIZE) {
pte_t *ptep = find_linux_pte_or_hugepte(mm->pgd, start, &is_thp,
&hugepage_shift);
pte_t *ptep = find_current_mm_pte(mm->pgd, start, &is_thp,
&hugepage_shift);
unsigned long pte;
if (ptep == NULL)

3
arch/powerpc/perf/callchain.c
View File

@ -22,6 +22,7 @@
#ifdef CONFIG_PPC64
#include "../kernel/ppc32.h"
#endif
#include <asm/pte-walk.h>
/*
@ -127,7 +128,7 @@ static int read_user_stack_slow(void __user *ptr, void *buf, int nb)
return -EFAULT;
local_irq_save(flags);
ptep = find_linux_pte_or_hugepte(pgdir, addr, NULL, &shift);
ptep = find_current_mm_pte(pgdir, addr, NULL, &shift);
if (!ptep)
goto err_out;
if (!shift)