[GIT PULL 3/9] KVM: s390: implement instruction execution protection for emulated ifetch

Christian Borntraeger
2017-06-28T17:30:38Z

While currently only used to fetch the original instruction on failure
for getting the instruction length code, we should make the page table
walking code future proof.

Suggested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
arch/s390/include/asm/ctl_reg.h | 4 +++-
arch/s390/kvm/gaccess.c | 39 +++++++++++++++++++++++++++++----------
2 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/arch/s390/include/asm/ctl_reg.h b/arch/s390/include/asm/ctl_reg.h
index d0441ad..e508dff 100644
--- a/arch/s390/include/asm/ctl_reg.h
+++ b/arch/s390/include/asm/ctl_reg.h
@@ -59,7 +59,9 @@ union ctlreg0 {
unsigned long lap : 1; /* Low-address-protection control */
unsigned long : 4;
unsigned long edat : 1; /* Enhanced-DAT-enablement control */
- unsigned long : 4;
+ unsigned long : 2;
+ unsigned long iep : 1; /* Instruction-Execution-Protection */
+ unsigned long : 1;
unsigned long afp : 1; /* AFP-register control */
unsigned long vx : 1; /* Vector enablement control */
unsigned long : 7;
diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
index 9da243d..6fda095 100644
--- a/arch/s390/kvm/gaccess.c
+++ b/arch/s390/kvm/gaccess.c
@@ -89,7 +89,7 @@ struct region3_table_entry_fc1 {
unsigned long f : 1; /* Fetch-Protection Bit */
unsigned long fc : 1; /* Format-Control */
unsigned long p : 1; /* DAT-Protection Bit */
- unsigned long co : 1; /* Change-Recording Override */
+ unsigned long iep: 1; /* Instruction-Execution-Protection */
unsigned long : 2;
unsigned long i : 1; /* Region-Invalid Bit */
unsigned long cr : 1; /* Common-Region Bit */
@@ -131,7 +131,7 @@ struct segment_entry_fc1 {
unsigned long f : 1; /* Fetch-Protection Bit */
unsigned long fc : 1; /* Format-Control */
unsigned long p : 1; /* DAT-Protection Bit */
- unsigned long co : 1; /* Change-Recording Override */
+ unsigned long iep: 1; /* Instruction-Execution-Protection */
unsigned long : 2;
unsigned long i : 1; /* Segment-Invalid Bit */
unsigned long cs : 1; /* Common-Segment Bit */
@@ -168,7 +168,8 @@ union page_table_entry {
unsigned long z : 1; /* Zero Bit */
unsigned long i : 1; /* Page-Invalid Bit */
unsigned long p : 1; /* DAT-Protection Bit */
- unsigned long : 9;
+ unsigned long iep: 1; /* Instruction-Execution-Protection */
+ unsigned long : 8;
};
};

@@ -485,6 +486,7 @@ enum prot_type {
PROT_TYPE_KEYC = 1,
PROT_TYPE_ALC = 2,
PROT_TYPE_DAT = 3,
+ PROT_TYPE_IEP = 4,
};

static int trans_exc(struct kvm_vcpu *vcpu, int code, unsigned long gva,
@@ -500,6 +502,9 @@ static int trans_exc(struct kvm_vcpu *vcpu, int code, unsigned long gva,
switch (code) {
case PGM_PROTECTION:
switch (prot) {
+ case PROT_TYPE_IEP:
+ tec->b61 = 1;
+ /* FALL THROUGH */
case PROT_TYPE_LA:
tec->b56 = 1;
break;
@@ -591,6 +596,7 @@ static int deref_table(struct kvm *kvm, unsigned long gpa, unsigned long *val)
* @gpa: points to where guest physical (absolute) address should be stored
* @asce: effective asce
* @mode: indicates the access mode to be used
+ * @prot: returns the type for protection exceptions
*
* Translate a guest virtual address into a guest absolute address by means
* of dynamic address translation as specified by the architecture.
@@ -606,19 +612,21 @@ static int deref_table(struct kvm *kvm, unsigned long gpa, unsigned long *val)
*/
static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
unsigned long *gpa, const union asce asce,
- enum gacc_mode mode)
+ enum gacc_mode mode, enum prot_type *prot)
{
union vaddress vaddr = {.addr = gva};
union raddress raddr = {.addr = gva};
union page_table_entry pte;
int dat_protection = 0;
+ int iep_protection = 0;
union ctlreg0 ctlreg0;
unsigned long ptr;
- int edat1, edat2;
+ int edat1, edat2, iep;

ctlreg0.val = vcpu->arch.sie_block->gcr[0];
edat1 = ctlreg0.edat && test_kvm_facility(vcpu->kvm, 8);
edat2 = edat1 && test_kvm_facility(vcpu->kvm, 78);
+ iep = ctlreg0.iep && test_kvm_facility(vcpu->kvm, 130);
if (asce.r)
goto real_address;
ptr = asce.origin * 4096;
@@ -702,6 +710,7 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
return PGM_TRANSLATION_SPEC;
if (rtte.fc && edat2) {
dat_protection |= rtte.fc1.p;
+ iep_protection = rtte.fc1.iep;
raddr.rfaa = rtte.fc1.rfaa;
goto absolute_address;
}
@@ -729,6 +738,7 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
return PGM_TRANSLATION_SPEC;
if (ste.fc && edat1) {
dat_protection |= ste.fc1.p;
+ iep_protection = ste.fc1.iep;
raddr.sfaa = ste.fc1.sfaa;
goto absolute_address;
}
@@ -745,12 +755,19 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
if (pte.z)
return PGM_TRANSLATION_SPEC;
dat_protection |= pte.p;
+ iep_protection = pte.iep;
raddr.pfra = pte.pfra;
real_address:
raddr.addr = kvm_s390_real_to_abs(vcpu, raddr.addr);
absolute_address:
- if (mode == GACC_STORE && dat_protection)
+ if (mode == GACC_STORE && dat_protection) {
+ *prot = PROT_TYPE_DAT;
return PGM_PROTECTION;
+ }
+ if (mode == GACC_IFETCH && iep_protection && iep) {
+ *prot = PROT_TYPE_IEP;
+ return PGM_PROTECTION;
+ }
if (kvm_is_error_gpa(vcpu->kvm, raddr.addr))
return PGM_ADDRESSING;
*gpa = raddr.addr;
@@ -782,6 +799,7 @@ static int guest_page_range(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
{
psw_t *psw = &vcpu->arch.sie_block->gpsw;
int lap_enabled, rc = 0;
+ enum prot_type prot;

lap_enabled = low_address_protection_enabled(vcpu, asce);
while (nr_pages) {
@@ -791,7 +809,7 @@ static int guest_page_range(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
PROT_TYPE_LA);
ga &= PAGE_MASK;
if (psw_bits(*psw).t) {
- rc = guest_translate(vcpu, ga, pages, asce, mode);
+ rc = guest_translate(vcpu, ga, pages, asce, mode, &prot);
if (rc < 0)
return rc;
} else {
@@ -800,7 +818,7 @@ static int guest_page_range(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
rc = PGM_ADDRESSING;
}
if (rc)
- return trans_exc(vcpu, rc, ga, ar, mode, PROT_TYPE_DAT);
+ return trans_exc(vcpu, rc, ga, ar, mode, prot);
ga += PAGE_SIZE;
pages++;
nr_pages--;
@@ -886,6 +904,7 @@ int guest_translate_address(struct kvm_vcpu *vcpu, unsigned long gva, u8 ar,
unsigned long *gpa, enum gacc_mode mode)
{
psw_t *psw = &vcpu->arch.sie_block->gpsw;
+ enum prot_type prot;
union asce asce;
int rc;

@@ -900,9 +919,9 @@ int guest_translate_address(struct kvm_vcpu *vcpu, unsigned long gva, u8 ar,
}

if (psw_bits(*psw).t && !asce.r) { /* Use DAT? */
- rc = guest_translate(vcpu, gva, gpa, asce, mode);
+ rc = guest_translate(vcpu, gva, gpa, asce, mode, &prot);
if (rc > 0)
- return trans_exc(vcpu, rc, gva, 0, mode, PROT_TYPE_DAT);
+ return trans_exc(vcpu, rc, gva, 0, mode, prot);
} else {
*gpa = kvm_s390_real_to_abs(vcpu, gva);
if (kvm_is_error_gpa(vcpu->kvm, *gpa))
--
2.7.4