[PATCH v6 06/21] KVM: s390: refactor crypto initialization

[Tony Krowiak]

From: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>

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 as long as the AP instructions are installed on the
   host.

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@xxxxxxxxxxxxx>
---
 arch/s390/include/asm/kvm_host.h |    3 +
 arch/s390/kvm/kvm-s390.c         |   85 +++++++++++++++++++------------------
 2 files changed, 47 insertions(+), 41 deletions(-)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index a2188e3..d44e0d5 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -186,6 +186,7 @@ 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
@@ -255,6 +256,7 @@ 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 */
@@ -713,6 +715,7 @@ struct kvm_s390_crypto {
 	__u32 crycbd;
 	__u8 aes_kw;
 	__u8 dea_kw;
+	__u8 apie;
 };
 
 #define APCB0_MASK_SIZE 1
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index d2208d4..3aa16df 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1886,49 +1886,37 @@ 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
@@ -1946,11 +1934,13 @@ 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;
@@ -2479,17 +2469,30 @@ 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))
 		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);
 
-	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)
-- 
1.7.1