Some facilities should only provided to the guest, if these are
enabled by a CPU model. This allows to avoid capabilities and
simply fallback to the cpumodel for deciding about a facility
without enabling it for older QEMUs or QEMUs without a CPU
model.
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
---
arch/s390/kvm/kvm-s390.c | 40 ++++++++++++++++++++++++++++++++--------
arch/s390/kvm/kvm-s390.h | 2 --
arch/s390/tools/gen_facilities.c | 20 ++++++++++++++++++++
3 files changed, 52 insertions(+), 10 deletions(-)
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 5b7fe80cda56..7d982690b1fc 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -151,13 +151,27 @@ static int nested;
module_param(nested, int, S_IRUGO);
MODULE_PARM_DESC(nested, "Nested virtualization support");
-/* upper facilities limit for kvm */
-unsigned long kvm_s390_fac_list_mask[16] = { FACILITIES_KVM };
-unsigned long kvm_s390_fac_list_mask_size(void)
+/*
+ * For now we handle not more than 16 double words as this is what
+ * the s390 base kernel handles and stores in prefix page. If we
+ * ever need to go beyond this, this requires changes to code, but
+ * the external uapi can stay.
+ */
+#define SIZE_INTERNAL 16
+
+/* upper facilities limit for kvm */
+static unsigned long kvm_s390_fac_list_mask[SIZE_INTERNAL] = { FACILITIES_KVM };
+/*
+ * facility bits that are in the mask, but initially not in the list.
+ * Those can be activated by the CPU model
+ */
+static unsigned long kvm_s390_fac_model[SIZE_INTERNAL] = { FACILITIES_KVM_CPUMODEL };
+
+static unsigned long kvm_s390_fac_size(void)
{
- BUILD_BUG_ON(ARRAY_SIZE(kvm_s390_fac_list_mask) > S390_ARCH_FAC_MASK_SIZE_U64);
- return ARRAY_SIZE(kvm_s390_fac_list_mask);
+ BUILD_BUG_ON(SIZE_INTERNAL > S390_ARCH_FAC_MASK_SIZE_U64);
+ return SIZE_INTERNAL;
}
/* available cpu features supported by kvm */
@@ -1946,17 +1960,27 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
memcpy(kvm->arch.model.fac_mask, S390_lowcore.stfle_fac_list,
sizeof(S390_lowcore.stfle_fac_list));
for (i = 0; i < S390_ARCH_FAC_LIST_SIZE_U64; i++) {
- if (i < kvm_s390_fac_list_mask_size())
- kvm->arch.model.fac_mask[i] &= kvm_s390_fac_list_mask[i];
+ if (i < kvm_s390_fac_size())
+ kvm->arch.model.fac_mask[i] &= (kvm_s390_fac_list_mask[i] |
+ kvm_s390_fac_model[i]);
else
kvm->arch.model.fac_mask[i] = 0UL;
}
- /* Populate the facility list initially. */
+ /* Populate the facility list initially as a copy of the mask */
kvm->arch.model.fac_list = kvm->arch.sie_page2->fac_list;
memcpy(kvm->arch.model.fac_list, kvm->arch.model.fac_mask,
S390_ARCH_FAC_LIST_SIZE_BYTE);
+ /*
+ * Disable facilities in the list that need CPU model support.
+ * Those are now in the mask but not in the list. Userspace can
+ * re-enable those that are in the mask via the CPU model
+ */
+ for (i = 0; i < S390_ARCH_FAC_LIST_SIZE_U64; i++)
+ if (i < kvm_s390_fac_size())
+ kvm->arch.model.fac_list[i] &= ~kvm_s390_fac_model[i];
+
/* we are always in czam mode - even on pre z14 machines */
set_kvm_facility(kvm->arch.model.fac_mask, 138);
set_kvm_facility(kvm->arch.model.fac_list, 138);
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index 3c0a975c2477..75efb6835acc 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -295,8 +295,6 @@ void exit_sie(struct kvm_vcpu *vcpu);
void kvm_s390_sync_request(int req, struct kvm_vcpu *vcpu);
int kvm_s390_vcpu_setup_cmma(struct kvm_vcpu *vcpu);
void kvm_s390_vcpu_unsetup_cmma(struct kvm_vcpu *vcpu);
-unsigned long kvm_s390_fac_list_mask_size(void);
-extern unsigned long kvm_s390_fac_list_mask[];
void kvm_s390_set_cpu_timer(struct kvm_vcpu *vcpu, __u64 cputm);
__u64 kvm_s390_get_cpu_timer(struct kvm_vcpu *vcpu);
diff --git a/arch/s390/tools/gen_facilities.c b/arch/s390/tools/gen_facilities.c
index 424a1ba4f874..37a77a3f280c 100644
--- a/arch/s390/tools/gen_facilities.c
+++ b/arch/s390/tools/gen_facilities.c
@@ -62,6 +62,13 @@ static struct facility_def facility_defs[] = {
}
},
{
+ /*
+ * FACILITIES_KVM contains the list of facilities that are
+ * part of the default facility mask and list passed to the
+ * initial CPU model. If no CPU model is used this, together
+ * with the non-hypervisor managed bits, is the maximum list
+ * of guest facilities supported by KVM.
+ */
.name = "FACILITIES_KVM",
.bits = (int[]){
0, /* N3 instructions */
@@ -89,6 +96,19 @@ static struct facility_def facility_defs[] = {
-1 /* END */
}
},
+ {
+ /*
+ * FACILITIES_KVM_CPUMODEL contains the list of facilities
+ * that can be enabled by CPU model code if the host supports
+ * it. These facilities are not passed to the guest without
+ * CPU model support.
+ */
+
+ .name = "FACILITIES_KVM_CPUMODEL",
+ .bits = (int[]){
+ -1 /* END */
+ }
+ },
};
static void print_facility_list(struct facility_def *def)
--
2.14.3
