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KVM: s390: Add skey emulation fault handling
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When doing skey emulation for huge guests, we now need to fault in
pmds, as we don't have PGSTES anymore to store them when we do not
have valid table entries.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
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Janosch Frank committed Jul 30, 2018
1 parent 637ff9e commit bd096f6
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Showing 2 changed files with 83 additions and 37 deletions.
15 changes: 12 additions & 3 deletions arch/s390/kvm/kvm-s390.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1551,6 +1551,7 @@ static long kvm_s390_set_skeys(struct kvm *kvm, struct kvm_s390_skeys *args)
uint8_t *keys;
uint64_t hva;
int srcu_idx, i, r = 0;
bool unlocked;

if (args->flags != 0)
return -EINVAL;
Expand All @@ -1575,9 +1576,11 @@ static long kvm_s390_set_skeys(struct kvm *kvm, struct kvm_s390_skeys *args)
if (r)
goto out;

i = 0;
down_read(&current->mm->mmap_sem);
srcu_idx = srcu_read_lock(&kvm->srcu);
for (i = 0; i < args->count; i++) {
while (i < args->count) {
unlocked = false;
hva = gfn_to_hva(kvm, args->start_gfn + i);
if (kvm_is_error_hva(hva)) {
r = -EFAULT;
Expand All @@ -1591,8 +1594,14 @@ static long kvm_s390_set_skeys(struct kvm *kvm, struct kvm_s390_skeys *args)
}

r = set_guest_storage_key(current->mm, hva, keys[i], 0);
if (r)
break;
if (r) {
r = fixup_user_fault(current, current->mm, hva,
FAULT_FLAG_WRITE, &unlocked);
if (r)
break;
}
if (!r)
i++;
}
srcu_read_unlock(&kvm->srcu, srcu_idx);
up_read(&current->mm->mmap_sem);
Expand Down
105 changes: 71 additions & 34 deletions arch/s390/kvm/priv.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -246,9 +246,10 @@ static int try_handle_skey(struct kvm_vcpu *vcpu)

static int handle_iske(struct kvm_vcpu *vcpu)
{
unsigned long addr;
unsigned long gaddr, vmaddr;
unsigned char key;
int reg1, reg2;
bool unlocked;
int rc;

vcpu->stat.instruction_iske++;
Expand All @@ -262,27 +263,38 @@ static int handle_iske(struct kvm_vcpu *vcpu)

kvm_s390_get_regs_rre(vcpu, &reg1, &reg2);

addr = vcpu->run->s.regs.gprs[reg2] & PAGE_MASK;
addr = kvm_s390_logical_to_effective(vcpu, addr);
addr = kvm_s390_real_to_abs(vcpu, addr);
addr = gfn_to_hva(vcpu->kvm, gpa_to_gfn(addr));
if (kvm_is_error_hva(addr))
gaddr = vcpu->run->s.regs.gprs[reg2] & PAGE_MASK;
gaddr = kvm_s390_logical_to_effective(vcpu, gaddr);
gaddr = kvm_s390_real_to_abs(vcpu, gaddr);
vmaddr = gfn_to_hva(vcpu->kvm, gpa_to_gfn(gaddr));
if (kvm_is_error_hva(vmaddr))
return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);

retry:
unlocked = false;
down_read(&current->mm->mmap_sem);
rc = get_guest_storage_key(current->mm, addr, &key);
up_read(&current->mm->mmap_sem);
rc = get_guest_storage_key(current->mm, vmaddr, &key);

if (rc) {
rc = fixup_user_fault(current, current->mm, vmaddr,
FAULT_FLAG_WRITE, &unlocked);
if (!rc) {
up_read(&current->mm->mmap_sem);
goto retry;
}
}
if (rc)
return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
up_read(&current->mm->mmap_sem);
vcpu->run->s.regs.gprs[reg1] &= ~0xff;
vcpu->run->s.regs.gprs[reg1] |= key;
return 0;
}

static int handle_rrbe(struct kvm_vcpu *vcpu)
{
unsigned long addr;
unsigned long vmaddr, gaddr;
int reg1, reg2;
bool unlocked;
int rc;

vcpu->stat.instruction_rrbe++;
Expand All @@ -296,19 +308,27 @@ static int handle_rrbe(struct kvm_vcpu *vcpu)

kvm_s390_get_regs_rre(vcpu, &reg1, &reg2);

addr = vcpu->run->s.regs.gprs[reg2] & PAGE_MASK;
addr = kvm_s390_logical_to_effective(vcpu, addr);
addr = kvm_s390_real_to_abs(vcpu, addr);
addr = gfn_to_hva(vcpu->kvm, gpa_to_gfn(addr));
if (kvm_is_error_hva(addr))
gaddr = vcpu->run->s.regs.gprs[reg2] & PAGE_MASK;
gaddr = kvm_s390_logical_to_effective(vcpu, gaddr);
gaddr = kvm_s390_real_to_abs(vcpu, gaddr);
vmaddr = gfn_to_hva(vcpu->kvm, gpa_to_gfn(gaddr));
if (kvm_is_error_hva(vmaddr))
return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);

retry:
unlocked = false;
down_read(&current->mm->mmap_sem);
rc = reset_guest_reference_bit(current->mm, addr);
up_read(&current->mm->mmap_sem);
rc = reset_guest_reference_bit(current->mm, vmaddr);
if (rc < 0) {
rc = fixup_user_fault(current, current->mm, vmaddr,
FAULT_FLAG_WRITE, &unlocked);
if (!rc) {
up_read(&current->mm->mmap_sem);
goto retry;
}
}
if (rc < 0)
return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);

up_read(&current->mm->mmap_sem);
kvm_s390_set_psw_cc(vcpu, rc);
return 0;
}
Expand All @@ -323,6 +343,7 @@ static int handle_sske(struct kvm_vcpu *vcpu)
unsigned long start, end;
unsigned char key, oldkey;
int reg1, reg2;
bool unlocked;
int rc;

vcpu->stat.instruction_sske++;
Expand Down Expand Up @@ -355,19 +376,28 @@ static int handle_sske(struct kvm_vcpu *vcpu)
}

while (start != end) {
unsigned long addr = gfn_to_hva(vcpu->kvm, gpa_to_gfn(start));
unsigned long vmaddr = gfn_to_hva(vcpu->kvm, gpa_to_gfn(start));
unlocked = false;

if (kvm_is_error_hva(addr))
if (kvm_is_error_hva(vmaddr))
return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);

down_read(&current->mm->mmap_sem);
rc = cond_set_guest_storage_key(current->mm, addr, key, &oldkey,
rc = cond_set_guest_storage_key(current->mm, vmaddr, key, &oldkey,
m3 & SSKE_NQ, m3 & SSKE_MR,
m3 & SSKE_MC);
up_read(&current->mm->mmap_sem);
if (rc < 0)

if (rc < 0) {
rc = fixup_user_fault(current, current->mm, vmaddr,
FAULT_FLAG_WRITE, &unlocked);
rc = !rc ? -EAGAIN : rc;
}
if (rc == -EFAULT)
return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
start += PAGE_SIZE;

up_read(&current->mm->mmap_sem);
if (rc >= 0)
start += PAGE_SIZE;
}

if (m3 & (SSKE_MC | SSKE_MR)) {
Expand Down Expand Up @@ -948,15 +978,16 @@ static int handle_pfmf(struct kvm_vcpu *vcpu)
}

while (start != end) {
unsigned long useraddr;
unsigned long vmaddr;
bool unlocked = false;

/* Translate guest address to host address */
useraddr = gfn_to_hva(vcpu->kvm, gpa_to_gfn(start));
if (kvm_is_error_hva(useraddr))
vmaddr = gfn_to_hva(vcpu->kvm, gpa_to_gfn(start));
if (kvm_is_error_hva(vmaddr))
return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);

if (vcpu->run->s.regs.gprs[reg1] & PFMF_CF) {
if (clear_user((void __user *)useraddr, PAGE_SIZE))
if (clear_user((void __user *)vmaddr, PAGE_SIZE))
return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
}

Expand All @@ -966,14 +997,20 @@ static int handle_pfmf(struct kvm_vcpu *vcpu)
if (rc)
return rc;
down_read(&current->mm->mmap_sem);
rc = cond_set_guest_storage_key(current->mm, useraddr,
rc = cond_set_guest_storage_key(current->mm, vmaddr,
key, NULL, nq, mr, mc);
up_read(&current->mm->mmap_sem);
if (rc < 0)
if (rc < 0) {
rc = fixup_user_fault(current, current->mm, vmaddr,
FAULT_FLAG_WRITE, &unlocked);
rc = !rc ? -EAGAIN : rc;
}
if (rc == -EFAULT)
return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
}

start += PAGE_SIZE;
up_read(&current->mm->mmap_sem);
if (rc >= 0)
start += PAGE_SIZE;
}
}
if (vcpu->run->s.regs.gprs[reg1] & PFMF_FSC) {
if (psw_bits(vcpu->arch.sie_block->gpsw).eaba == PSW_BITS_AMODE_64BIT) {
Expand Down

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