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Message-ID: <7df88bde-2b63-4a91-036c-28527f56e22d@linux.ibm.com>
Date: Fri, 10 Dec 2021 14:27:01 +0100
From: Christian Borntraeger <borntraeger@...ux.ibm.com>
To: Matthew Rosato <mjrosato@...ux.ibm.com>, linux-s390@...r.kernel.org
Cc: alex.williamson@...hat.com, cohuck@...hat.com,
schnelle@...ux.ibm.com, farman@...ux.ibm.com, pmorel@...ux.ibm.com,
hca@...ux.ibm.com, gor@...ux.ibm.com,
gerald.schaefer@...ux.ibm.com, agordeev@...ux.ibm.com,
frankja@...ux.ibm.com, david@...hat.com, imbrenda@...ux.ibm.com,
vneethv@...ux.ibm.com, oberpar@...ux.ibm.com, freude@...ux.ibm.com,
thuth@...hat.com, pasic@...ux.ibm.com, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 19/32] KVM: s390: mechanism to enable guest zPCI
Interpretation
Am 07.12.21 um 21:57 schrieb Matthew Rosato:
> The guest must have access to certain facilities in order to allow
> interpretive execution of zPCI instructions and adapter event
> notifications. However, there are some cases where a guest might
> disable interpretation -- provide a mechanism via which we can defer
> enabling the associated zPCI interpretation facilities until the guest
> indicates it wishes to use them.
>
> Signed-off-by: Matthew Rosato <mjrosato@...ux.ibm.com>
> ---
> arch/s390/include/asm/kvm_host.h | 4 +++
> arch/s390/kvm/kvm-s390.c | 43 ++++++++++++++++++++++++++++++++
> arch/s390/kvm/kvm-s390.h | 10 ++++++++
> 3 files changed, 57 insertions(+)
>
> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
> index 3f147b8d050b..38982c1de413 100644
> --- a/arch/s390/include/asm/kvm_host.h
> +++ b/arch/s390/include/asm/kvm_host.h
> @@ -252,7 +252,10 @@ struct kvm_s390_sie_block {
> #define ECB2_IEP 0x20
> #define ECB2_PFMFI 0x08
> #define ECB2_ESCA 0x04
> +#define ECB2_ZPCI_LSI 0x02
> __u8 ecb2; /* 0x0062 */
> +#define ECB3_AISI 0x20
> +#define ECB3_AISII 0x10
> #define ECB3_DEA 0x08
> #define ECB3_AES 0x04
> #define ECB3_RI 0x01
> @@ -938,6 +941,7 @@ struct kvm_arch{
> int use_cmma;
> int use_pfmfi;
> int use_skf;
> + int use_zpci_interp;
> int user_cpu_state_ctrl;
> int user_sigp;
> int user_stsi;
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index a680f2a02b67..361d742cdf0d 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -1023,6 +1023,47 @@ static int kvm_s390_vm_set_crypto(struct kvm *kvm, struct kvm_device_attr *attr)
> return 0;
> }
>
> +static void kvm_s390_vcpu_pci_setup(struct kvm_vcpu *vcpu)
> +{
> + /*
> + * If the facilities aren't available for PCI interpretation and
> + * interrupt forwarding, we shouldn't be here.
> + */
This reads like we want a WARN_ON or BUG_ON, but as we call this uncoditionally this is
actually a valid check. So instead of "shouldn't be here" say something like "bail out
if interpretion is not active". ?
> + if (!vcpu->kvm->arch.use_zpci_interp)
> + return;
> +
> + vcpu->arch.sie_block->ecb2 |= ECB2_ZPCI_LSI;
> + vcpu->arch.sie_block->ecb3 |= ECB3_AISII + ECB3_AISI;
> +}
> +
> +void kvm_s390_vcpu_pci_enable_interp(struct kvm *kvm)
> +{
> + struct kvm_vcpu *vcpu;
> + int i;
> +
> + /*
> + * If host facilities are available, turn on interpretation for the
> + * life of this guest
> + */
> + if (!test_facility(69) || !test_facility(70) || !test_facility(71) ||
> + !test_facility(72))
> + return;
Wouldnt that also enable interpretion for VSIE? I guess we should check for the
sclp facilities from patches 1,2,3, and 4 instead.
> +
> + mutex_lock(&kvm->lock);
> +
> + kvm->arch.use_zpci_interp = 1;
> +
> + kvm_s390_vcpu_block_all(kvm);
> +
> + kvm_for_each_vcpu(i, vcpu, kvm) {
> + kvm_s390_vcpu_pci_setup(vcpu);
> + kvm_s390_sync_request(KVM_REQ_VSIE_RESTART, vcpu);
> + }
> +
> + kvm_s390_vcpu_unblock_all(kvm);
> + mutex_unlock(&kvm->lock);
> +}
> +
> static void kvm_s390_sync_request_broadcast(struct kvm *kvm, int req)
> {
> int cx;
> @@ -3288,6 +3329,8 @@ static int kvm_s390_vcpu_setup(struct kvm_vcpu *vcpu)
> h
> kvm_s390_vcpu_crypto_setup(vcpu);
>
> + kvm_s390_vcpu_pci_setup(vcpu);
> +
> mutex_lock(&vcpu->kvm->lock);
> if (kvm_s390_pv_is_protected(vcpu->kvm)) {
> rc = kvm_s390_pv_create_cpu(vcpu, &uvrc, &uvrrc);
> diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
> index c07a050d757d..a2eccb8b977e 100644
> --- a/arch/s390/kvm/kvm-s390.h
> +++ b/arch/s390/kvm/kvm-s390.h
> @@ -481,6 +481,16 @@ void kvm_s390_reinject_machine_check(struct kvm_vcpu *vcpu,
> */
> void kvm_s390_vcpu_crypto_reset_all(struct kvm *kvm);
>
> +/**
> + * kvm_s390_vcpu_pci_enable_interp
> + *
> + * Set the associated PCI attributes for each vcpu to allow for zPCI Load/Store
> + * interpretation as well as adapter interruption forwarding.
> + *
> + * @kvm: the KVM guest
> + */
> +void kvm_s390_vcpu_pci_enable_interp(struct kvm *kvm);
> +
> /**
> * diag9c_forwarding_hz
> *
>
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