New version below. Changes:
- __pmdp_for_addr and ptep_for_addr now take a vma as argument
- check if a vma exists has moved to gmap_fault and kvm_s390_keyop
- kvm_s390_keyop verifies that a vma is writable so that it's safe to
set the SWC bit
Subject: [PATCH] kvm-s390: storage key interface
From: Carsten Otte <cotte@xxxxxxxxxx>
This patch introduces an interface to access the guest visible
storage keys. It supports three operations that model the behavior
that SSKE/ISKE/RRBE instructions would have if they were issued by
the guest. These instructions are all documented in the z architecture
principles of operation book.
Signed-off-by: Carsten Otte <cotte@xxxxxxxxxx>
---
---
Documentation/virtual/kvm/api.txt | 38 ++++++++++++++
arch/s390/include/asm/kvm_host.h | 4 +
arch/s390/include/asm/pgtable.h | 1
arch/s390/kvm/kvm-s390.c | 103 ++++++++++++++++++++++++++++++++++++--
arch/s390/mm/pgtable.c | 70 +++++++++++++++++++------
include/linux/kvm.h | 7 ++
6 files changed, 202 insertions(+), 21 deletions(-)
Index: linux-2.5-cecsim/Documentation/virtual/kvm/api.txt
===================================================================
--- linux-2.5-cecsim.orig/Documentation/virtual/kvm/api.txt
+++ linux-2.5-cecsim/Documentation/virtual/kvm/api.txt
@@ -1494,6 +1494,44 @@ table upfront. This is useful to handle
controlled virtual machines to fault in the virtual cpu's lowcore pages
prior to calling the KVM_RUN ioctl.
+4.67 KVM_S390_KEYOP
+
+Capability: KVM_CAP_S390_UCONTROL
+Architectures: s390
+Type: vm ioctl
+Parameters: struct kvm_s390_keyop (in+out)
+Returns: 0 in case of success
+
+The parameter looks like this:
+ struct kvm_s390_keyop {
+ __u64 user_addr;
+ __u8 key;
+ __u8 operation;
+ };
+
+user_addr contains the userspace address of a memory page
+key contains the guest visible storage key as defined by the
+ z Architecture Principles of Operation book, including key
+ value for key controlled storage protection, the fetch
+ protection bit, and the reference and change indicator bits
+operation indicates the key operation that should be performed
+
+The following operations are supported:
+KVM_S390_KEYOP_SSKE:
+ This operation behaves just like the set storage key extended (SSKE)
+ instruction would, if it were issued by the guest. The storage key
+ provided in "key" is placed in the guest visible storage key.
+KVM_S390_KEYOP_ISKE:
+ This operation behaves just like the insert storage key extended (ISKE)
+ instruction would, if it were issued by the guest. After this call,
+ the guest visible storage key is presented in the "key" field.
+KVM_S390_KEYOP_RRBE:
+ This operation behaves just like the reset referenced bit extended
+ (RRBE) instruction would, if it were issued by the guest. The guest
+ visible reference bit is cleared, and the value presented in the "key"
+ field after this call has the reference bit set to 1 in case the
+ guest view of the reference bit was 1 prior to this call.
+
5. The kvm_run structure
Application code obtains a pointer to the kvm_run structure by
Index: linux-2.5-cecsim/arch/s390/include/asm/kvm_host.h
===================================================================
--- linux-2.5-cecsim.orig/arch/s390/include/asm/kvm_host.h
+++ linux-2.5-cecsim/arch/s390/include/asm/kvm_host.h
@@ -24,6 +24,10 @@
/* memory slots that does not exposed to userspace */
#define KVM_PRIVATE_MEM_SLOTS 4
+#define KVM_S390_KEYOP_SSKE 0x01
+#define KVM_S390_KEYOP_ISKE 0x02
+#define KVM_S390_KEYOP_RRBE 0x03
+
struct sca_entry {
atomic_t scn;
__u32 reserved;
Index: linux-2.5-cecsim/arch/s390/include/asm/pgtable.h
===================================================================
--- linux-2.5-cecsim.orig/arch/s390/include/asm/pgtable.h
+++ linux-2.5-cecsim/arch/s390/include/asm/pgtable.h
@@ -1237,6 +1237,7 @@ static inline pte_t mk_swap_pte(unsigned
extern int vmem_add_mapping(unsigned long start, unsigned long size);
extern int vmem_remove_mapping(unsigned long start, unsigned long size);
extern int s390_enable_sie(void);
+extern pte_t *ptep_for_addr(unsigned long addr, struct vm_area_struct *);
/*
* No page table caches to initialise
Index: linux-2.5-cecsim/arch/s390/kvm/kvm-s390.c
===================================================================
--- linux-2.5-cecsim.orig/arch/s390/kvm/kvm-s390.c
+++ linux-2.5-cecsim/arch/s390/kvm/kvm-s390.c
@@ -112,13 +112,127 @@ void kvm_arch_exit(void)
{
}
+static long kvm_s390_keyop(struct kvm_s390_keyop *kop)
+{
+ struct vm_area_struct *vma;
+ unsigned long addr = kop->user_addr;
+ pte_t *ptep;
+ pgste_t pgste;
+ int r;
+ unsigned long skey;
+ unsigned long bits;
+
+ /* make sure this process is a hypervisor */
+ r = -EINVAL;
+ if (!mm_has_pgste(current->mm))
+ goto out;
+
+ r = -EFAULT;
+ if (addr >= PGDIR_SIZE)
+ goto out;
+
+ down_read(¤t->mm->mmap_sem);
+ r = -EFAULT;
+ vma = find_vma(current->mm, addr);
+ if (!vma || (vma->vm_start > addr))
+ goto out_unlock;
+
+ ptep = ptep_for_addr(addr, vma);
+ if (IS_ERR(ptep)) {
+ r = PTR_ERR(ptep);
+ goto out_unlock;
+ }
+
+ spin_lock(¤t->mm->page_table_lock);
+ pgste = pgste_get_lock(ptep);
+
+ switch (kop->operation) {
+ case KVM_S390_KEYOP_SSKE:
+ if (!(vma->vm_flags & (VM_WRITE | VM_MAYWRITE))) {
+ r = -EACCES;
+ break;
+ }
+ pgste = pgste_update_all(ptep, pgste);
+ /* set the real key back w/o rc bits */
+ skey = kop->key & (_PAGE_ACC_BITS | _PAGE_FP_BIT);
+ if (pte_present(*ptep)) {
+ page_set_storage_key(pte_val(*ptep), skey, 1);
+ /* avoid race clobbering changed bit */
+ pte_val(*ptep) |= _PAGE_SWC;
+ }
+ /* put acc+f plus guest referenced and changed into the pgste */
+ pgste_val(pgste) &= ~(RCP_ACC_BITS | RCP_FP_BIT | RCP_GR_BIT
+ | RCP_GC_BIT);
+ bits = (kop->key & (_PAGE_ACC_BITS | _PAGE_FP_BIT));
+ pgste_val(pgste) |= bits << 56;
+ bits = (kop->key & (_PAGE_CHANGED | _PAGE_REFERENCED));
+ pgste_val(pgste) |= bits << 48;
+ r = 0;
+ break;
+ case KVM_S390_KEYOP_ISKE:
+ if (pte_present(*ptep)) {
+ skey = page_get_storage_key(pte_val(*ptep));
+ kop->key = skey & (_PAGE_ACC_BITS | _PAGE_FP_BIT);
+ } else {
+ skey = 0;
+ kop->key = (pgste_val(pgste) >> 56) &
+ (_PAGE_ACC_BITS | _PAGE_FP_BIT);
+ }
+ kop->key |= skey & (_PAGE_CHANGED | _PAGE_REFERENCED);
+ kop->key |= (pgste_val(pgste) >> 48) &
+ (_PAGE_CHANGED | _PAGE_REFERENCED);
+ r = 0;
+ break;
+ case KVM_S390_KEYOP_RRBE:
+ pgste = pgste_update_all(ptep, pgste);
+ kop->key = 0;
+ if (pgste_val(pgste) & RCP_GR_BIT)
+ kop->key |= _PAGE_REFERENCED;
+ pgste_val(pgste) &= ~RCP_GR_BIT;
+ r = 0;
+ break;
+ default:
+ r = -EINVAL;
+ }
+ pgste_set_unlock(ptep, pgste);
+ spin_unlock(¤t->mm->page_table_lock);
+
+out_unlock:
+ up_read(¤t->mm->mmap_sem);
+out:
+ return r;
+}
+
/* Section: device related */
long kvm_arch_dev_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg)
{
- if (ioctl == KVM_S390_ENABLE_SIE)
- return s390_enable_sie();
- return -EINVAL;
+ void __user *argp = (void __user *)arg;
+ int r;
+
+ switch (ioctl) {
+ case KVM_S390_ENABLE_SIE:
+ r = s390_enable_sie();
+ break;
+ case KVM_S390_KEYOP: {
+ struct kvm_s390_keyop kop;
+ r = -EFAULT;
+ if (copy_from_user(&kop, argp, sizeof(struct kvm_s390_keyop)))
+ break;
+ r = kvm_s390_keyop(&kop);
+ if (r)
+ break;
+ r = -EFAULT;
+ if (copy_to_user(argp, &kop, sizeof(struct kvm_s390_keyop)))
+ break;
+ r = 0;
+ break;
+ }
+ default:
+ r = -ENOTTY;
+ }
+
+ return r;
}
int kvm_dev_ioctl_check_extension(long ext)
Index: linux-2.5-cecsim/arch/s390/mm/pgtable.c
===================================================================
--- linux-2.5-cecsim.orig/arch/s390/mm/pgtable.c
+++ linux-2.5-cecsim/arch/s390/mm/pgtable.c
@@ -382,6 +382,29 @@ out_unmap:
}
EXPORT_SYMBOL_GPL(gmap_map_segment);
+static pmd_t *__pmdp_for_addr(struct mm_struct *mm, struct vm_area_struct *vma,
+ unsigned long addr)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+
+ pgd = pgd_offset(mm, addr);
+ pud = pud_alloc(mm, pgd, addr);
+ if (!pud)
+ return ERR_PTR(-ENOMEM);
+
+ pmd = pmd_alloc(mm, pud, addr);
+ if (!pmd)
+ return ERR_PTR(-ENOMEM);
+
+ if (!pmd_present(*pmd) &&
+ __pte_alloc(mm, vma, pmd, addr))
+ return ERR_PTR(-ENOMEM);
+
+ return pmd;
+}
+
/*
* this function is assumed to be called with mmap_sem held
*/
@@ -391,10 +414,8 @@ unsigned long __gmap_fault(unsigned long
struct mm_struct *mm;
struct gmap_pgtable *mp;
struct gmap_rmap *rmap;
- struct vm_area_struct *vma;
struct page *page;
- pgd_t *pgd;
- pud_t *pud;
+ struct vm_area_struct *vma;
pmd_t *pmd;
current->thread.gmap_addr = address;
@@ -422,21 +443,15 @@ unsigned long __gmap_fault(unsigned long
return mp->vmaddr | (address & ~PMD_MASK);
} else if (segment & _SEGMENT_ENTRY_RO) {
vmaddr = segment & _SEGMENT_ENTRY_ORIGIN;
+
vma = find_vma(mm, vmaddr);
- if (!vma || vma->vm_start > vmaddr)
+ if (!vma || (vma->vm_start > vmaddr))
return -EFAULT;
- /* Walk the parent mm page table */
- pgd = pgd_offset(mm, vmaddr);
- pud = pud_alloc(mm, pgd, vmaddr);
- if (!pud)
- return -ENOMEM;
- pmd = pmd_alloc(mm, pud, vmaddr);
- if (!pmd)
- return -ENOMEM;
- if (!pmd_present(*pmd) &&
- __pte_alloc(mm, vma, pmd, vmaddr))
- return -ENOMEM;
+ pmd = __pmdp_for_addr(mm, vma, vmaddr);
+ if (IS_ERR(pmd))
+ return PTR_ERR(pmd);
+
/* pmd now points to a valid segment table entry. */
rmap = kmalloc(sizeof(*rmap), GFP_KERNEL|__GFP_REPEAT);
if (!rmap)
@@ -795,6 +810,20 @@ int s390_enable_sie(void)
}
EXPORT_SYMBOL_GPL(s390_enable_sie);
+pte_t *ptep_for_addr(unsigned long addr, struct vm_area_struct *vma)
+{
+ pmd_t *pmd;
+ pte_t *pte;
+
+ pmd = __pmdp_for_addr(current->mm, vma, addr);
+ if (IS_ERR(pmd))
+ return (pte_t *)pmd;
+
+ pte = pte_offset(pmd, addr);
+ return pte;
+}
+EXPORT_SYMBOL_GPL(ptep_for_addr);
+
#if defined(CONFIG_DEBUG_PAGEALLOC) && defined(CONFIG_HIBERNATION)
bool kernel_page_present(struct page *page)
{
Index: linux-2.5-cecsim/include/linux/kvm.h
===================================================================
--- linux-2.5-cecsim.orig/include/linux/kvm.h
+++ linux-2.5-cecsim/include/linux/kvm.h
@@ -450,6 +450,13 @@ struct kvm_ppc_pvinfo {
#define KVM_GET_MSR_INDEX_LIST _IOWR(KVMIO, 0x02, struct kvm_msr_list)
#define KVM_S390_ENABLE_SIE _IO(KVMIO, 0x06)
+
+struct kvm_s390_keyop {
+ __u64 user_addr;
+ __u8 key;
+ __u8 operation;
+};
+#define KVM_S390_KEYOP _IOWR(KVMIO, 0x09, struct kvm_s390_keyop)
/*
* Check if a kvm extension is available. Argument is extension number,
* return is 1 (yes) or 0 (no, sorry).
--
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