powerpc/mm: Rename find_linux_pte_or_hugepte()

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

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 *));

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 */

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);

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 {

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))

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)

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;

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;

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);

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;

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)

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)

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@ -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)