KVM: s390: Optimize paths where get_vcpu_asce() is invoked

During dynamic address translation the get_vcpu_asce()
function can be invoked several times. It's ok for usual modes, but will
be slow if CPUs are in AR mode. Let's call the get_vcpu_asce() once and
pass the result to the called functions.

Signed-off-by: Alexander Yarygin <yarygin@linux.vnet.ibm.com>
Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

1 files changed, 12 insertions, 13 deletions

diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
index 494131eda8c1..c74462a12c6d 100644
--- a/arch/s390/kvm/gaccess.c
+++ b/arch/s390/kvm/gaccess.c
@@ -330,6 +330,7 @@ static int deref_table(struct kvm *kvm, unsigned long gpa, unsigned long *val)
  * @vcpu: virtual cpu
  * @gva: guest virtual address
  * @gpa: points to where guest physical (absolute) address should be stored
+ * @asce: effective asce
  * @write: indicates if access is a write access
  *
  * Translate a guest virtual address into a guest absolute address by means
@@ -345,7 +346,8 @@ static int deref_table(struct kvm *kvm, unsigned long gpa, unsigned long *val)
  *            by the architecture
  */
 static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
-                                     unsigned long *gpa, int write)
+                                     unsigned long *gpa, const union asce asce,
+                                     int write)
 {
         union vaddress vaddr = {.addr = gva};
         union raddress raddr = {.addr = gva};
@@ -354,12 +356,10 @@ static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
         union ctlreg0 ctlreg0;
         unsigned long ptr;
         int edat1, edat2;
-        union asce asce;
 
         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);
-        asce.val = get_vcpu_asce(vcpu);
         if (asce.r)
                 goto real_address;
         ptr = asce.origin * 4096;
@@ -506,15 +506,14 @@ static inline int is_low_address(unsigned long ga)
         return (ga & ~0x11fful) == 0;
 }
 
-static int low_address_protection_enabled(struct kvm_vcpu *vcpu)
+static int low_address_protection_enabled(struct kvm_vcpu *vcpu,
+                                          const union asce asce)
 {
         union ctlreg0 ctlreg0 = {.val = vcpu->arch.sie_block->gcr[0]};
         psw_t *psw = &vcpu->arch.sie_block->gpsw;
-        union asce asce;
 
         if (!ctlreg0.lap)
                 return 0;
-        asce.val = get_vcpu_asce(vcpu);
         if (psw_bits(*psw).t && asce.p)
                 return 0;
         return 1;
@@ -536,7 +535,7 @@ enum {
 
 static int guest_page_range(struct kvm_vcpu *vcpu, unsigned long ga,
                             unsigned long *pages, unsigned long nr_pages,
-                            int write)
+                            const union asce asce, int write)
 {
         struct kvm_s390_pgm_info *pgm = &vcpu->arch.pgm;
         psw_t *psw = &vcpu->arch.sie_block->gpsw;
@@ -547,7 +546,7 @@ static int guest_page_range(struct kvm_vcpu *vcpu, unsigned long ga,
         tec_bits = (struct trans_exc_code_bits *)&pgm->trans_exc_code;
         tec_bits->fsi = write ? FSI_STORE : FSI_FETCH;
         tec_bits->as = psw_bits(*psw).as;
-        lap_enabled = low_address_protection_enabled(vcpu);
+        lap_enabled = low_address_protection_enabled(vcpu, asce);
         while (nr_pages) {
                 ga = kvm_s390_logical_to_effective(vcpu, ga);
                 tec_bits->addr = ga >> PAGE_SHIFT;
@@ -557,7 +556,7 @@ static int guest_page_range(struct kvm_vcpu *vcpu, unsigned long ga,
                 }
                 ga &= PAGE_MASK;
                 if (psw_bits(*psw).t) {
-                        rc = guest_translate(vcpu, ga, pages, write);
+                        rc = guest_translate(vcpu, ga, pages, asce, write);
                         if (rc < 0)
                                 return rc;
                         if (rc == PGM_PROTECTION)
@@ -604,7 +603,7 @@ int access_guest(struct kvm_vcpu *vcpu, unsigned long ga, ar_t ar, void *data,
         need_ipte_lock = psw_bits(*psw).t && !asce.r;
         if (need_ipte_lock)
                 ipte_lock(vcpu);
-        rc = guest_page_range(vcpu, ga, pages, nr_pages, write);
+        rc = guest_page_range(vcpu, ga, pages, nr_pages, asce, write);
         for (idx = 0; idx < nr_pages && !rc; idx++) {
                 gpa = *(pages + idx) + (ga & ~PAGE_MASK);
                 _len = min(PAGE_SIZE - (gpa & ~PAGE_MASK), len);
@@ -671,16 +670,16 @@ int guest_translate_address(struct kvm_vcpu *vcpu, unsigned long gva, ar_t ar,
         tec->as = psw_bits(*psw).as;
         tec->fsi = write ? FSI_STORE : FSI_FETCH;
         tec->addr = gva >> PAGE_SHIFT;
-        if (is_low_address(gva) && low_address_protection_enabled(vcpu)) {
+        asce.val = get_vcpu_asce(vcpu);
+        if (is_low_address(gva) && low_address_protection_enabled(vcpu, asce)) {
                 if (write) {
                         rc = pgm->code = PGM_PROTECTION;
                         return rc;
                 }
         }
 
-        asce.val = get_vcpu_asce(vcpu);
         if (psw_bits(*psw).t && !asce.r) {      /* Use DAT? */
-                rc = guest_translate(vcpu, gva, gpa, write);
+                rc = guest_translate(vcpu, gva, gpa, asce, write);
                 if (rc > 0) {
                         if (rc == PGM_PROTECTION)
                                 tec->b61 = 1;