Messages in this thread | | | Subject | Re: [PATCH v5 02/13] KVM: s390: refactor crypto initialization | From | Pierre Morel <> | Date | Wed, 16 May 2018 14:17:52 +0200 |
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On 16/05/2018 13:14, Tony Krowiak wrote: > On 05/16/2018 04:51 AM, Pierre Morel wrote: >> On 07/05/2018 17:11, Tony Krowiak wrote: >>> This patch refactors the code that initializes the crypto >>> configuration for a guest. The crypto configuration is contained in >>> a crypto control block (CRYCB) which is a satellite control block to >>> our main hardware virtualization control block. The CRYCB is >>> attached to the main virtualization control block via a CRYCB >>> designation (CRYCBD) designation field containing the address of >>> the CRYCB as well as its format. >>> >>> Prior to the introduction of AP device virtualization, there was >>> no need to provide access to or specify the format of the CRYCB for >>> a guest unless the MSA extension 3 (MSAX3) facility was installed >>> on the host system. With the introduction of AP device virtualization, >>> the CRYCB and its format must be made accessible to the guest >>> regardless of the presence of the MSAX3 facility as long as the >>> AP instructions are installed on the host. >>> >>> Signed-off-by: Tony Krowiak <akrowiak@linux.vnet.ibm.com> >>> --- >>> arch/s390/include/asm/kvm_host.h | 1 + >>> arch/s390/kvm/kvm-s390.c | 64 >>> ++++++++++++++++++++++++++----------- >>> 2 files changed, 46 insertions(+), 19 deletions(-) >>> >>> diff --git a/arch/s390/include/asm/kvm_host.h >>> b/arch/s390/include/asm/kvm_host.h >>> index 81cdb6b..5393c4d 100644 >>> --- a/arch/s390/include/asm/kvm_host.h >>> +++ b/arch/s390/include/asm/kvm_host.h >>> @@ -255,6 +255,7 @@ 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 */ >>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c >>> index 1f50de7..99779a6 100644 >>> --- a/arch/s390/kvm/kvm-s390.c >>> +++ b/arch/s390/kvm/kvm-s390.c >>> @@ -1875,14 +1875,35 @@ long kvm_arch_vm_ioctl(struct file *filp, >>> return r; >>> } >>> >>> -static void kvm_s390_set_crycb_format(struct kvm *kvm) >>> +/* >>> + * 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_format_crycb(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_ap_apxa_installed()) >>> kvm->arch.crypto.crycbd |= CRYCB_FORMAT2; >>> else >>> kvm->arch.crypto.crycbd |= CRYCB_FORMAT1; >>> + one lin >>> + /* Enable AES/DEA protected key functions by default */ >>> + kvm->arch.crypto.aes_kw = 1; >>> + kvm->arch.crypto.dea_kw = 1; >>> + get_random_bytes(kvm->arch.crypto.crycb->aes_wrapping_key_mask, >>> + sizeof(kvm->arch.crypto.crycb->aes_wrapping_key_mask)); >>> + get_random_bytes(kvm->arch.crypto.crycb->dea_wrapping_key_mask, >>> + sizeof(kvm->arch.crypto.crycb->dea_wrapping_key_mask)); >>> } >>> >>> static u64 kvm_s390_get_initial_cpuid(void) >>> @@ -1896,19 +1917,17 @@ static u64 kvm_s390_get_initial_cpuid(void) >>> >>> static void kvm_s390_crypto_init(struct kvm *kvm) >>> { >>> - if (!test_kvm_facility(kvm, 76)) >>> + /* >>> + * If neither the AP instructions nor the message security assist >>> + * extension 3 (MSAX3) are installed, there is no need to >>> initialize a >>> + * crypto control block (CRYCB) for the guest. >>> + */ >>> + if (!kvm_ap_instructions_available() && !test_kvm_facility(kvm, >>> 76)) >>> return; >>> >>> kvm->arch.crypto.crycb = &kvm->arch.sie_page2->crycb; >>> - kvm_s390_set_crycb_format(kvm); >> >> >> For my point of view the all patch can be reduced to putting this >> call (kvm_s390_set_crycb_format(kvm);) before testing for facility 76. >> >> (and setting the format correctly in kvm_s390_set_crycb_format(kvm)) > > I don't see what that buys us; it will just be reshuffling of the logic. > The idea here is that all of the code related to formatting the CRYCB for > use by the guest is contained in the kvm_s390_format_crycb(kvm) function. > We don't need a CRYCB, however, if the AP instructions are not installed > and the MSAX3 facility is not installed, so why even call > kvm_s390_format_crycb(kvm) in that case?
It byes a lot of lines. I mean that you do exactly the same by only using 3 lines inserted instead of 65 changes. No logic change.
> >> >> >> >>> - >>> - /* Enable AES/DEA protected key functions by default */ >>> - kvm->arch.crypto.aes_kw = 1; >>> - kvm->arch.crypto.dea_kw = 1; >>> - get_random_bytes(kvm->arch.crypto.crycb->aes_wrapping_key_mask, >>> - sizeof(kvm->arch.crypto.crycb->aes_wrapping_key_mask)); >>> - get_random_bytes(kvm->arch.crypto.crycb->dea_wrapping_key_mask, >>> - sizeof(kvm->arch.crypto.crycb->dea_wrapping_key_mask)); >>> + kvm->arch.crypto.crycbd = (__u32)(unsigned long) >>> kvm->arch.crypto.crycb; >>> + kvm_s390_format_crycb(kvm); >>> } >>> >>> static void sca_dispose(struct kvm *kvm) >>> @@ -2430,17 +2449,24 @@ 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 a crypto control block designation (CRYCBD) has not been >>> + * initialized >>> + */ >>> + if (vcpu->kvm->arch.crypto.crycbd == 0) >>> return; >>> >>> - vcpu->arch.sie_block->ecb3 &= ~(ECB3_AES | ECB3_DEA); >>> + 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; >>> + /* If MSAX3 is installed, set up protected key support */ >>> + if (test_kvm_facility(vcpu->kvm, 76)) { >>> + vcpu->arch.sie_block->ecb3 &= ~(ECB3_AES | ECB3_DEA); >>> >>> - 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) >> >> >
-- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany
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