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s390/kvm: Add PGSTE manipulation functions

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Add PGSTE manipulation functions:
* set_pgste_bits sets specific bits in a PGSTE
* get_pgste returns the whole PGSTE
* pgste_perform_essa manipulates a PGSTE to set specific storage states
* ESSA_[SG]ET_* macros used to indicate the action for manipulate_pgste

Signed-off-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
Reviewed-by: Janosch Frank <frankja@de.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Claudio Imbrenda 2017-04-20 10:03:45 +02:00 committed by Martin Schwidefsky
parent b13de4b7ad
commit 2d42f94773
4 changed files with 185 additions and 6 deletions
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19
arch/s390/include/asm/page-states.h Normal file
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@ -0,0 +1,19 @@
/*
* Copyright IBM Corp. 2017
* Author(s): Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
*/
#ifndef PAGE_STATES_H
#define PAGE_STATES_H
#define ESSA_GET_STATE 0
#define ESSA_SET_STABLE 1
#define ESSA_SET_UNUSED 2
#define ESSA_SET_VOLATILE 3
#define ESSA_SET_POT_VOLATILE 4
#define ESSA_SET_STABLE_RESIDENT 5
#define ESSA_SET_STABLE_IF_RESIDENT 6
#define ESSA_MAX ESSA_SET_STABLE_IF_RESIDENT
#endif

16
arch/s390/include/asm/pgtable.h
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@ -372,10 +372,12 @@ static inline int is_module_addr(void *addr)
#define PGSTE_VSIE_BIT 0x0000200000000000UL /* ref'd in a shadow table */
/* Guest Page State used for virtualization */
#define _PGSTE_GPS_ZERO 0x0000000080000000UL
#define _PGSTE_GPS_USAGE_MASK 0x0000000003000000UL
#define _PGSTE_GPS_USAGE_STABLE 0x0000000000000000UL
#define _PGSTE_GPS_USAGE_UNUSED 0x0000000001000000UL
#define _PGSTE_GPS_ZERO 0x0000000080000000UL
#define _PGSTE_GPS_USAGE_MASK 0x0000000003000000UL
#define _PGSTE_GPS_USAGE_STABLE 0x0000000000000000UL
#define _PGSTE_GPS_USAGE_UNUSED 0x0000000001000000UL
#define _PGSTE_GPS_USAGE_POT_VOLATILE 0x0000000002000000UL
#define _PGSTE_GPS_USAGE_VOLATILE _PGSTE_GPS_USAGE_MASK
/*
* A user page table pointer has the space-switch-event bit, the
@ -1041,6 +1043,12 @@ int reset_guest_reference_bit(struct mm_struct *mm, unsigned long addr);
int get_guest_storage_key(struct mm_struct *mm, unsigned long addr,
unsigned char *key);
int set_pgste_bits(struct mm_struct *mm, unsigned long addr,
unsigned long bits, unsigned long value);
int get_pgste(struct mm_struct *mm, unsigned long hva, unsigned long *pgstep);
int pgste_perform_essa(struct mm_struct *mm, unsigned long hva, int orc,
unsigned long *oldpte, unsigned long *oldpgste);
/*
* Certain architectures need to do special things when PTEs
* within a page table are directly modified. Thus, the following

3
arch/s390/mm/page-states.c
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@ -13,8 +13,7 @@
#include <linux/gfp.h>
#include <linux/init.h>
#define ESSA_SET_STABLE 1
#define ESSA_SET_UNUSED 2
#include <asm/page-states.h>
static int cmma_flag = 1;

153
arch/s390/mm/pgtable.c
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@ -23,6 +23,7 @@
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <asm/page-states.h>
static inline pte_t ptep_flush_direct(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
@ -787,4 +788,156 @@ int get_guest_storage_key(struct mm_struct *mm, unsigned long addr,
return 0;
}
EXPORT_SYMBOL(get_guest_storage_key);
/**
* pgste_perform_essa - perform ESSA actions on the PGSTE.
* @mm: the memory context. It must have PGSTEs, no check is performed here!
* @hva: the host virtual address of the page whose PGSTE is to be processed
* @orc: the specific action to perform, see the ESSA_SET_* macros.
* @oldpte: the PTE will be saved there if the pointer is not NULL.
* @oldpgste: the old PGSTE will be saved there if the pointer is not NULL.
*
* Return: 1 if the page is to be added to the CBRL, otherwise 0,
* or < 0 in case of error. -EINVAL is returned for invalid values
* of orc, -EFAULT for invalid addresses.
*/
int pgste_perform_essa(struct mm_struct *mm, unsigned long hva, int orc,
unsigned long *oldpte, unsigned long *oldpgste)
{
unsigned long pgstev;
spinlock_t *ptl;
pgste_t pgste;
pte_t *ptep;
int res = 0;
WARN_ON_ONCE(orc > ESSA_MAX);
if (unlikely(orc > ESSA_MAX))
return -EINVAL;
ptep = get_locked_pte(mm, hva, &ptl);
if (unlikely(!ptep))
return -EFAULT;
pgste = pgste_get_lock(ptep);
pgstev = pgste_val(pgste);
if (oldpte)
*oldpte = pte_val(*ptep);
if (oldpgste)
*oldpgste = pgstev;
switch (orc) {
case ESSA_GET_STATE:
break;
case ESSA_SET_STABLE:
pgstev &= ~_PGSTE_GPS_USAGE_MASK;
pgstev |= _PGSTE_GPS_USAGE_STABLE;
break;
case ESSA_SET_UNUSED:
pgstev &= ~_PGSTE_GPS_USAGE_MASK;
pgstev |= _PGSTE_GPS_USAGE_UNUSED;
if (pte_val(*ptep) & _PAGE_INVALID)
res = 1;
break;
case ESSA_SET_VOLATILE:
pgstev &= ~_PGSTE_GPS_USAGE_MASK;
pgstev |= _PGSTE_GPS_USAGE_VOLATILE;
if (pte_val(*ptep) & _PAGE_INVALID)
res = 1;
break;
case ESSA_SET_POT_VOLATILE:
pgstev &= ~_PGSTE_GPS_USAGE_MASK;
if (!(pte_val(*ptep) & _PAGE_INVALID)) {
pgstev |= _PGSTE_GPS_USAGE_POT_VOLATILE;
break;
}
if (pgstev & _PGSTE_GPS_ZERO) {
pgstev |= _PGSTE_GPS_USAGE_VOLATILE;
break;
}
if (!(pgstev & PGSTE_GC_BIT)) {
pgstev |= _PGSTE_GPS_USAGE_VOLATILE;
res = 1;
break;
}
break;
case ESSA_SET_STABLE_RESIDENT:
pgstev &= ~_PGSTE_GPS_USAGE_MASK;
pgstev |= _PGSTE_GPS_USAGE_STABLE;
/*
* Since the resident state can go away any time after this
* call, we will not make this page resident. We can revisit
* this decision if a guest will ever start using this.
*/
break;
case ESSA_SET_STABLE_IF_RESIDENT:
if (!(pte_val(*ptep) & _PAGE_INVALID)) {
pgstev &= ~_PGSTE_GPS_USAGE_MASK;
pgstev |= _PGSTE_GPS_USAGE_STABLE;
}
break;
default:
/* we should never get here! */
break;
}
/* If we are discarding a page, set it to logical zero */
if (res)
pgstev |= _PGSTE_GPS_ZERO;
pgste_val(pgste) = pgstev;
pgste_set_unlock(ptep, pgste);
pte_unmap_unlock(ptep, ptl);
return res;
}
EXPORT_SYMBOL(pgste_perform_essa);
/**
* set_pgste_bits - set specific PGSTE bits.
* @mm: the memory context. It must have PGSTEs, no check is performed here!
* @hva: the host virtual address of the page whose PGSTE is to be processed
* @bits: a bitmask representing the bits that will be touched
* @value: the values of the bits to be written. Only the bits in the mask
* will be written.
*
* Return: 0 on success, < 0 in case of error.
*/
int set_pgste_bits(struct mm_struct *mm, unsigned long hva,
unsigned long bits, unsigned long value)
{
spinlock_t *ptl;
pgste_t new;
pte_t *ptep;
ptep = get_locked_pte(mm, hva, &ptl);
if (unlikely(!ptep))
return -EFAULT;
new = pgste_get_lock(ptep);
pgste_val(new) &= ~bits;
pgste_val(new) |= value & bits;
pgste_set_unlock(ptep, new);
pte_unmap_unlock(ptep, ptl);
return 0;
}
EXPORT_SYMBOL(set_pgste_bits);
/**
* get_pgste - get the current PGSTE for the given address.
* @mm: the memory context. It must have PGSTEs, no check is performed here!
* @hva: the host virtual address of the page whose PGSTE is to be processed
* @pgstep: will be written with the current PGSTE for the given address.
*
* Return: 0 on success, < 0 in case of error.
*/
int get_pgste(struct mm_struct *mm, unsigned long hva, unsigned long *pgstep)
{
spinlock_t *ptl;
pte_t *ptep;
ptep = get_locked_pte(mm, hva, &ptl);
if (unlikely(!ptep))
return -EFAULT;
*pgstep = pgste_val(pgste_get(ptep));
pte_unmap_unlock(ptep, ptl);
return 0;
}
EXPORT_SYMBOL(get_pgste);
#endif