[patch 10/12] [PATCH] kvm-s390: storage key interface

[Carsten Otte <cotte@de.ibm.com>]

[-- Attachment #1: skey.patch --]
[-- Type: text/plain, Size: 5037 bytes --]

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@de.ibm.com>
---
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
@@ -25,6 +25,9 @@
 #define KVM_PRIVATE_MEM_SLOTS 4
 
 #define KVM_SIE_PAGE_OFFSET 1
+#define KVM_S390_KEYOP_SSKE 0x01
+#define KVM_S390_KEYOP_ISKE 0x02
+#define KVM_S390_KEYOP_RRBE 0x03
 
 struct sca_entry {
 	atomic_t scn;
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 +112,144 @@ void kvm_arch_exit(void)
 {
 }
 
+pte_t *ptep_for_addr(unsigned long addr)
+{
+	struct vm_area_struct *vma;
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *rc;
+
+	down_read(&current->mm->mmap_sem);
+
+	rc = NULL;
+	vma = find_vma(current->mm, addr);
+	if (!vma)
+		goto up_out;
+
+	pgd = pgd_offset(current->mm, addr);
+	pud = pud_alloc(current->mm, pgd, addr);
+	if (!pud)
+		goto up_out;
+
+	pmd = pmd_alloc(current->mm, pud, addr);
+	if (!pmd)
+		goto up_out;
+
+	if (!pmd_present(*pmd) &&
+	    __pte_alloc(current->mm, vma, pmd, addr))
+		goto up_out;
+
+	rc = pte_offset(pmd, addr);
+up_out:
+	up_read(&current->mm->mmap_sem);
+	return rc;
+}
+
+static long kvm_s390_keyop(struct kvm_s390_keyop *kop)
+{
+	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 = -ENXIO;
+	if (addr >= PGDIR_SIZE)
+		goto out;
+
+	spin_lock(&current->mm->page_table_lock);
+	ptep = ptep_for_addr(addr);
+	if (!ptep)
+		goto out_unlock;
+
+	pgste = pgste_get_lock(ptep);
+
+	switch (kop->operation) {
+	case KVM_S390_KEYOP_SSKE:
+		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);
+		/* put acc+f plus guest refereced 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);
+
+out_unlock:
+	spin_unlock(&current->mm->page_table_lock);
+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/include/linux/kvm.h
===================================================================
--- linux-2.5-cecsim.orig/include/linux/kvm.h
+++ linux-2.5-cecsim/include/linux/kvm.h
@@ -445,6 +445,13 @@ 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).