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KVM: s390: implement CPU model only facilities

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Some facilities should only be provided to the guest, if they are
enabled by a CPU model. This allows us to avoid capabilities and
to simply fall back to the cpumodel for deciding about a facility
without enabling it for older QEMUs or QEMUs without a CPU
model.

Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
Christian Borntraeger 2018-02-09 16:26:29 +00:00
parent f07afa0462
commit c3b9e3e1ea
3 changed files with 54 additions and 21 deletions
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53
arch/s390/kvm/kvm-s390.c
View File

@ -152,13 +152,33 @@ 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 at most 16 double words as this is what the s390 base
* kernel handles and stores in the 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
/*
* Base feature mask that defines default mask for facilities. Consists of the
* defines in FACILITIES_KVM and the non-hypervisor managed bits.
*/
static unsigned long kvm_s390_fac_base[SIZE_INTERNAL] = { FACILITIES_KVM };
/*
* Extended feature mask. Consists of the defines in FACILITIES_KVM_CPUMODEL
* and defines the facilities that can be enabled via a cpu model.
*/
static unsigned long kvm_s390_fac_ext[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);
BUILD_BUG_ON(SIZE_INTERNAL > S390_ARCH_FAC_LIST_SIZE_U64);
BUILD_BUG_ON(SIZE_INTERNAL * sizeof(unsigned long) >
sizeof(S390_lowcore.stfle_fac_list));
return SIZE_INTERNAL;
}
/* available cpu features supported by kvm */
@ -1967,20 +1987,15 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
if (!kvm->arch.sie_page2)
goto out_err;
/* Populate the facility mask initially. */
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];
else
kvm->arch.model.fac_mask[i] = 0UL;
}
/* Populate the facility list initially. */
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);
for (i = 0; i < kvm_s390_fac_size(); i++) {
kvm->arch.model.fac_mask[i] = S390_lowcore.stfle_fac_list[i] &
(kvm_s390_fac_base[i] |
kvm_s390_fac_ext[i]);
kvm->arch.model.fac_list[i] = S390_lowcore.stfle_fac_list[i] &
kvm_s390_fac_base[i];
}
/* we are always in czam mode - even on pre z14 machines */
set_kvm_facility(kvm->arch.model.fac_mask, 138);
@ -4044,7 +4059,7 @@ static int __init kvm_s390_init(void)
}
for (i = 0; i < 16; i++)
kvm_s390_fac_list_mask[i] |=
kvm_s390_fac_base[i] |=
S390_lowcore.stfle_fac_list[i] & nonhyp_mask(i);
return kvm_init(NULL, sizeof(struct kvm_vcpu), 0, THIS_MODULE);

2
arch/s390/kvm/kvm-s390.h
View File

@ -294,8 +294,6 @@ 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);

20
arch/s390/tools/gen_facilities.c
View File

@ -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 that are 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)