Re: [PATCH v8 07/22] KVM: s390: refactor crypto initialization

Tony Krowiak
2018-08-09T19:54:25Z

On 08/09/2018 04:25 AM, David Hildenbrand wrote:
> On 08.08.2018 16:44, Tony Krowiak wrote:
>> From: Tony Krowiak <akrowiak@linux.ibm.com>
>>
>> This patch refactors the code that initializes and sets up the
>> crypto configuration for a guest. The following changes are
>> implemented via this patch:
>>
>> 1. Prior to the introduction of AP device virtualization, it
>> was not necessary to provide guest access to the CRYCB
>> unless the MSA extension 3 (MSAX3) facility was installed
>> on the host system. With the introduction of AP device
>> virtualization, the CRYCB must be made accessible to the
>> guest if the AP instructions are installed on the host
>> and are to be provided to the guest.
>>
>> 2. Introduces a flag indicating AP instructions executed on
>> the guest shall be interpreted by the firmware. It is
>> initialized to indicate AP instructions are to be
>> to be interpreted and is used to set the SIE bit for
>> each vcpu during vcpu setup.
>>
>> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
>> Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
>> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
>> Tested-by: Michael Mueller <mimu@linux.ibm.com>
>> Tested-by: Farhan Ali <alifm@linux.ibm.com>
>> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
>> ---
>> arch/s390/include/asm/kvm_host.h | 3 +
>> arch/s390/include/uapi/asm/kvm.h | 1 +
>> arch/s390/kvm/kvm-s390.c | 86 ++++++++++++++++++++------------------
>> 3 files changed, 49 insertions(+), 41 deletions(-)
>>
>> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
>> index af39561..0c13f61 100644
>> --- a/arch/s390/include/asm/kvm_host.h
>> +++ b/arch/s390/include/asm/kvm_host.h
>> @@ -187,6 +187,7 @@ struct kvm_s390_sie_block {
>> #define ECA_AIV 0x00200000
>> #define ECA_VX 0x00020000
>> #define ECA_PROTEXCI 0x00002000
>> +#define ECA_APIE 0x00000008
>> #define ECA_SII 0x00000001
>> __u32 eca; /* 0x004c */
>> #define ICPT_INST 0x04
>> @@ -256,6 +257,7 @@ struct kvm_s390_sie_block {
>> __u8 reservede4[4]; /* 0x00e4 */
>> __u64 tecmc; /* 0x00e8 */
>> __u8 reservedf0[12]; /* 0x00f0 */
>> +#define CRYCB_FORMAT_MASK 0x00000003
>> #define CRYCB_FORMAT1 0x00000001
>> #define CRYCB_FORMAT2 0x00000003
>> __u32 crycbd; /* 0x00fc */
>> @@ -714,6 +716,7 @@ struct kvm_s390_crypto {
>> __u32 crycbd;
>> __u8 aes_kw;
>> __u8 dea_kw;
>> + __u8 apie;
>
> This flag is essentially always 1 as far as I can see, so please drop it
> for now. (can be introduced when really needed)

That would appear to be true, so it probably makes sense to drop it.

>
>> };
>>
>> #define APCB0_MASK_SIZE 1
>> diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
>> index 4cdaa55..a580dec 100644
>> --- a/arch/s390/include/uapi/asm/kvm.h
>> +++ b/arch/s390/include/uapi/asm/kvm.h
>> @@ -130,6 +130,7 @@ struct kvm_s390_vm_cpu_machine {
>> #define KVM_S390_VM_CPU_FEAT_PFMFI 11
>> #define KVM_S390_VM_CPU_FEAT_SIGPIF 12
>> #define KVM_S390_VM_CPU_FEAT_KSS 13
>> +#define KVM_S390_VM_CPU_FEAT_AP 14
>> struct kvm_s390_vm_cpu_feat {
>> __u64 feat[16];
>> };
>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>> index 19f4f44..f96a443 100644
>> --- a/arch/s390/kvm/kvm-s390.c
>> +++ b/arch/s390/kvm/kvm-s390.c
>> @@ -40,6 +40,7 @@
>> #include <asm/sclp.h>
>> #include <asm/cpacf.h>
>> #include <asm/timex.h>
>> +#include <asm/ap.h>
>> #include "kvm-s390.h"
>> #include "gaccess.h"
>>
>> @@ -1881,49 +1882,37 @@ long kvm_arch_vm_ioctl(struct file *filp,
>> return r;
>> }
>>
>> -static int kvm_s390_query_ap_config(u8 *config)
>> -{
>> - u32 fcn_code = 0x04000000UL;
>> - u32 cc = 0;
>> -
>> - memset(config, 0, 128);
>> - asm volatile(
>> - "lgr 0,%1\n"
>> - "lgr 2,%2\n"
>> - ".long 0xb2af0000\n" /* PQAP(QCI) */
>> - "0: ipm %0\n"
>> - "srl %0,28\n"
>> - "1:\n"
>> - EX_TABLE(0b, 1b)
>> - : "+r" (cc)
>> - : "r" (fcn_code), "r" (config)
>> - : "cc", "0", "2", "memory"
>> - );
>> -
>> - return cc;
>> -}
>> -
>> static int kvm_s390_apxa_installed(void)
>> {
>> - u8 config[128];
>> - int cc;
>> + struct ap_config_info info;
>>
>> - if (test_facility(12)) {
>> - cc = kvm_s390_query_ap_config(config);
>> -
>> - if (cc)
>> - pr_err("PQAP(QCI) failed with cc=%d", cc);
>> - else
>> - return config[0] & 0x40;
>> + if (ap_instructions_available() == 0) {
>> + if (ap_qci(&info) == 0)
>> + return info.apxa;
>> }
>>
>> return 0;
>> }
>>
>> +/*
>> + * The format of the crypto control block (CRYCB) is specified in the 3 low
>> + * order bits of the CRYCB designation (CRYCBD) field as follows:
>> + * Format 0: Neither the message security assist extension 3 (MSAX3) nor the
>> + * AP extended addressing (APXA) facility are installed.
>> + * Format 1: The APXA facility is not installed but the MSAX3 facility is.
>> + * Format 2: Both the APXA and MSAX3 facilities are installed
>> + */
>> static void kvm_s390_set_crycb_format(struct kvm *kvm)
>> {
>> kvm->arch.crypto.crycbd = (__u32)(unsigned long) kvm->arch.crypto.crycb;
>>
>> + /* Clear the CRYCB format bits - i.e., set format 0 by default */
>> + kvm->arch.crypto.crycbd &= ~(CRYCB_FORMAT_MASK);
>> +
>> + /* Check whether MSAX3 is installed */
>> + if (!test_kvm_facility(kvm, 76))
>> + return;
>> +
>> if (kvm_s390_apxa_installed())
>> kvm->arch.crypto.crycbd |= CRYCB_FORMAT2;
>> else
>> @@ -1941,11 +1930,13 @@ static u64 kvm_s390_get_initial_cpuid(void)
>>
>> static void kvm_s390_crypto_init(struct kvm *kvm)
>> {
>> - if (!test_kvm_facility(kvm, 76))
>> - return;
>> -
>> kvm->arch.crypto.crycb = &kvm->arch.sie_page2->crycb;
>> kvm_s390_set_crycb_format(kvm);
>> + /* Default setting indicating SIE shall interpret AP instructions */
>> + kvm->arch.crypto.apie = 1;
>> +
>> + if (!test_kvm_facility(kvm, 76))
>> + return;
>>
>> /* Enable AES/DEA protected key functions by default */
>> kvm->arch.crypto.aes_kw = 1;
>> @@ -2474,17 +2465,30 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
>>
>> static void kvm_s390_vcpu_crypto_setup(struct kvm_vcpu *vcpu)
>> {
>> - if (!test_kvm_facility(vcpu->kvm, 76))
>> + /*
>> + * If neither the AP instructions nor the MSAX3 facility are installed
>> + * on the host, then there is no need for a CRYCB in SIE because the
>> + * they will not be installed on the guest either.
>> + */
>> + if (ap_instructions_available() && !test_facility(76))
> Why not turn this into
>
> if (!test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_AP) &&
> !test_kvm_facility(vcpu->kvm, 76))
>
> These properties should no longer change at this point. And we simulate
> exactly what the guest will see. No crycb needed. And even no comment
> needed.

That sounds reasonable, I will make the change.

>
>
>> return;
>>
>> - vcpu->arch.sie_block->ecb3 &= ~(ECB3_AES | ECB3_DEA);
>> + vcpu->arch.sie_block->crycbd = vcpu->kvm->arch.crypto.crycbd;
>> +
>> + vcpu->arch.sie_block->eca &= ~ECA_APIE;
>> + if (vcpu->kvm->arch.crypto.apie &&
>> + test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_AP))
>> + vcpu->arch.sie_block->eca |= ECA_APIE;
>>
>> - if (vcpu->kvm->arch.crypto.aes_kw)
>> - vcpu->arch.sie_block->ecb3 |= ECB3_AES;
>> - if (vcpu->kvm->arch.crypto.dea_kw)
>> - vcpu->arch.sie_block->ecb3 |= ECB3_DEA;
>> + /* If MSAX3 is installed on the guest, set up protected key support */
>> + if (test_kvm_facility(vcpu->kvm, 76)) {
>> + vcpu->arch.sie_block->ecb3 &= ~(ECB3_AES | ECB3_DEA);
> Why not keep the original unconditional clearing?

No good reason that I can think of ... I'll restore that.

>
>>
>> - vcpu->arch.sie_block->crycbd = vcpu->kvm->arch.crypto.crycbd;
>> + if (vcpu->kvm->arch.crypto.aes_kw)
>> + vcpu->arch.sie_block->ecb3 |= ECB3_AES;
>> + if (vcpu->kvm->arch.crypto.dea_kw)
>> + vcpu->arch.sie_block->ecb3 |= ECB3_DEA;
>> + }
>> }
>>
>> void kvm_s390_vcpu_unsetup_cmma(struct kvm_vcpu *vcpu)
>>
>