[RFC 26/37] KVM: s390: protvirt: Only sync fmt4 registers

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A lot of the registers are controlled by the Ultravisor and never
visible to KVM. Also some registers are overlayed, like gbea is with
sidad, which might leak data to userspace.

Hence we sync a minimal set of registers for both SIE formats and then
check and sync format 2 registers if necessary.

Also we disable set/get one reg for the same reason. It's an old
interface anyway.

Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
---
 arch/s390/kvm/kvm-s390.c | 138 +++++++++++++++++++++++----------------
 1 file changed, 82 insertions(+), 56 deletions(-)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 17a78774c617..f623c64aeade 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2997,7 +2997,8 @@ static void kvm_s390_vcpu_initial_reset(struct kvm_vcpu *vcpu)
 	/* make sure the new fpc will be lazily loaded */
 	save_fpu_regs();
 	current->thread.fpu.fpc = 0;
-	vcpu->arch.sie_block->gbea = 1;
+	if (!kvm_s390_pv_is_protected(vcpu->kvm))
+		vcpu->arch.sie_block->gbea = 1;
 	vcpu->arch.sie_block->pp = 0;
 	vcpu->arch.sie_block->fpf &= ~FPF_BPBC;
 	vcpu->arch.pfault_token = KVM_S390_PFAULT_TOKEN_INVALID;
@@ -3367,6 +3368,10 @@ static int kvm_arch_vcpu_ioctl_get_one_reg(struct kvm_vcpu *vcpu,
 			     (u64 __user *)reg->addr);
 		break;
 	case KVM_REG_S390_GBEA:
+		if (kvm_s390_pv_is_protected(vcpu->kvm)) {
+			r = 0;
+			break;
+		}
 		r = put_user(vcpu->arch.sie_block->gbea,
 			     (u64 __user *)reg->addr);
 		break;
@@ -3420,6 +3425,10 @@ static int kvm_arch_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu,
 			     (u64 __user *)reg->addr);
 		break;
 	case KVM_REG_S390_GBEA:
+		if (kvm_s390_pv_is_protected(vcpu->kvm)) {
+			r = 0;
+			break;
+		}
 		r = get_user(vcpu->arch.sie_block->gbea,
 			     (u64 __user *)reg->addr);
 		break;
@@ -4023,28 +4032,19 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
 	return rc;
 }
 
-static void sync_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
+static void sync_regs_fmt2(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 {
 	struct runtime_instr_cb *riccb;
 	struct gs_cb *gscb;
 
 	riccb = (struct runtime_instr_cb *) &kvm_run->s.regs.riccb;
 	gscb = (struct gs_cb *) &kvm_run->s.regs.gscb;
-	vcpu->arch.sie_block->gpsw.mask = kvm_run->psw_mask;
-	vcpu->arch.sie_block->gpsw.addr = kvm_run->psw_addr;
-	if (kvm_run->kvm_dirty_regs & KVM_SYNC_PREFIX)
-		kvm_s390_set_prefix(vcpu, kvm_run->s.regs.prefix);
-	if (kvm_run->kvm_dirty_regs & KVM_SYNC_CRS) {
-		memcpy(&vcpu->arch.sie_block->gcr, &kvm_run->s.regs.crs, 128);
-		/* some control register changes require a tlb flush */
-		kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
-	}
-	if (kvm_run->kvm_dirty_regs & KVM_SYNC_ARCH0) {
-		kvm_s390_set_cpu_timer(vcpu, kvm_run->s.regs.cputm);
-		vcpu->arch.sie_block->ckc = kvm_run->s.regs.ckc;
-		vcpu->arch.sie_block->todpr = kvm_run->s.regs.todpr;
-		vcpu->arch.sie_block->pp = kvm_run->s.regs.pp;
-		vcpu->arch.sie_block->gbea = kvm_run->s.regs.gbea;
+	if (kvm_run->kvm_dirty_regs & KVM_SYNC_ARCH0)
+		  vcpu->arch.sie_block->gbea = kvm_run->s.regs.gbea;
+	if ((kvm_run->kvm_dirty_regs & KVM_SYNC_BPBC) &&
+	    test_kvm_facility(vcpu->kvm, 82)) {
+		vcpu->arch.sie_block->fpf &= ~FPF_BPBC;
+		vcpu->arch.sie_block->fpf |= kvm_run->s.regs.bpbc ? FPF_BPBC : 0;
 	}
 	if (kvm_run->kvm_dirty_regs & KVM_SYNC_PFAULT) {
 		vcpu->arch.pfault_token = kvm_run->s.regs.pft;
@@ -4077,25 +4077,6 @@ static void sync_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 		vcpu->arch.sie_block->ecd |= ECD_HOSTREGMGMT;
 		vcpu->arch.gs_enabled = 1;
 	}
-	if ((kvm_run->kvm_dirty_regs & KVM_SYNC_BPBC) &&
-	    test_kvm_facility(vcpu->kvm, 82)) {
-		vcpu->arch.sie_block->fpf &= ~FPF_BPBC;
-		vcpu->arch.sie_block->fpf |= kvm_run->s.regs.bpbc ? FPF_BPBC : 0;
-	}
-	save_access_regs(vcpu->arch.host_acrs);
-	restore_access_regs(vcpu->run->s.regs.acrs);
-	/* save host (userspace) fprs/vrs */
-	save_fpu_regs();
-	vcpu->arch.host_fpregs.fpc = current->thread.fpu.fpc;
-	vcpu->arch.host_fpregs.regs = current->thread.fpu.regs;
-	if (MACHINE_HAS_VX)
-		current->thread.fpu.regs = vcpu->run->s.regs.vrs;
-	else
-		current->thread.fpu.regs = vcpu->run->s.regs.fprs;
-	current->thread.fpu.fpc = vcpu->run->s.regs.fpc;
-	if (test_fp_ctl(current->thread.fpu.fpc))
-		/* User space provided an invalid FPC, let's clear it */
-		current->thread.fpu.fpc = 0;
 	if (MACHINE_HAS_GS) {
 		preempt_disable();
 		__ctl_set_bit(2, 4);
@@ -4111,33 +4092,50 @@ static void sync_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 		preempt_enable();
 	}
 	/* SIE will load etoken directly from SDNX and therefore kvm_run */
+}
 
+static void sync_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
+{
+	vcpu->arch.sie_block->gpsw.mask = kvm_run->psw_mask;
+	vcpu->arch.sie_block->gpsw.addr = kvm_run->psw_addr;
+	if (kvm_run->kvm_dirty_regs & KVM_SYNC_PREFIX)
+		kvm_s390_set_prefix(vcpu, kvm_run->s.regs.prefix);
+	if (kvm_run->kvm_dirty_regs & KVM_SYNC_CRS) {
+		memcpy(&vcpu->arch.sie_block->gcr, &kvm_run->s.regs.crs, 128);
+		/* some control register changes require a tlb flush */
+		kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
+	}
+	if (kvm_run->kvm_dirty_regs & KVM_SYNC_ARCH0) {
+		kvm_s390_set_cpu_timer(vcpu, kvm_run->s.regs.cputm);
+		vcpu->arch.sie_block->ckc = kvm_run->s.regs.ckc;
+		vcpu->arch.sie_block->todpr = kvm_run->s.regs.todpr;
+		vcpu->arch.sie_block->pp = kvm_run->s.regs.pp;
+	}
+	save_access_regs(vcpu->arch.host_acrs);
+	restore_access_regs(vcpu->run->s.regs.acrs);
+	/* save host (userspace) fprs/vrs */
+	save_fpu_regs();
+	vcpu->arch.host_fpregs.fpc = current->thread.fpu.fpc;
+	vcpu->arch.host_fpregs.regs = current->thread.fpu.regs;
+	if (MACHINE_HAS_VX)
+		current->thread.fpu.regs = vcpu->run->s.regs.vrs;
+	else
+		current->thread.fpu.regs = vcpu->run->s.regs.fprs;
+	current->thread.fpu.fpc = vcpu->run->s.regs.fpc;
+	if (test_fp_ctl(current->thread.fpu.fpc))
+		/* User space provided an invalid FPC, let's clear it */
+		current->thread.fpu.fpc = 0;
+
+	/* Sync fmt2 only data */
+	if (likely(!kvm_s390_pv_is_protected(vcpu->kvm)))
+		sync_regs_fmt2(vcpu, kvm_run);
 	kvm_run->kvm_dirty_regs = 0;
 }
 
-static void store_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
+static void store_regs_fmt2(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 {
-	kvm_run->psw_mask = vcpu->arch.sie_block->gpsw.mask;
-	kvm_run->psw_addr = vcpu->arch.sie_block->gpsw.addr;
-	kvm_run->s.regs.prefix = kvm_s390_get_prefix(vcpu);
-	memcpy(&kvm_run->s.regs.crs, &vcpu->arch.sie_block->gcr, 128);
-	kvm_run->s.regs.cputm = kvm_s390_get_cpu_timer(vcpu);
-	kvm_run->s.regs.ckc = vcpu->arch.sie_block->ckc;
-	kvm_run->s.regs.todpr = vcpu->arch.sie_block->todpr;
-	kvm_run->s.regs.pp = vcpu->arch.sie_block->pp;
 	kvm_run->s.regs.gbea = vcpu->arch.sie_block->gbea;
-	kvm_run->s.regs.pft = vcpu->arch.pfault_token;
-	kvm_run->s.regs.pfs = vcpu->arch.pfault_select;
-	kvm_run->s.regs.pfc = vcpu->arch.pfault_compare;
 	kvm_run->s.regs.bpbc = (vcpu->arch.sie_block->fpf & FPF_BPBC) == FPF_BPBC;
-	save_access_regs(vcpu->run->s.regs.acrs);
-	restore_access_regs(vcpu->arch.host_acrs);
-	/* Save guest register state */
-	save_fpu_regs();
-	vcpu->run->s.regs.fpc = current->thread.fpu.fpc;
-	/* Restore will be done lazily at return */
-	current->thread.fpu.fpc = vcpu->arch.host_fpregs.fpc;
-	current->thread.fpu.regs = vcpu->arch.host_fpregs.regs;
 	if (MACHINE_HAS_GS) {
 		__ctl_set_bit(2, 4);
 		if (vcpu->arch.gs_enabled)
@@ -4153,6 +4151,31 @@ static void store_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	/* SIE will save etoken directly into SDNX and therefore kvm_run */
 }
 
+static void store_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
+{
+	kvm_run->psw_mask = vcpu->arch.sie_block->gpsw.mask;
+	kvm_run->psw_addr = vcpu->arch.sie_block->gpsw.addr;
+	kvm_run->s.regs.prefix = kvm_s390_get_prefix(vcpu);
+	memcpy(&kvm_run->s.regs.crs, &vcpu->arch.sie_block->gcr, 128);
+	kvm_run->s.regs.cputm = kvm_s390_get_cpu_timer(vcpu);
+	kvm_run->s.regs.ckc = vcpu->arch.sie_block->ckc;
+	kvm_run->s.regs.todpr = vcpu->arch.sie_block->todpr;
+	kvm_run->s.regs.pp = vcpu->arch.sie_block->pp;
+	kvm_run->s.regs.pft = vcpu->arch.pfault_token;
+	kvm_run->s.regs.pfs = vcpu->arch.pfault_select;
+	kvm_run->s.regs.pfc = vcpu->arch.pfault_compare;
+	save_access_regs(vcpu->run->s.regs.acrs);
+	restore_access_regs(vcpu->arch.host_acrs);
+	/* Save guest register state */
+	save_fpu_regs();
+	vcpu->run->s.regs.fpc = current->thread.fpu.fpc;
+	/* Restore will be done lazily at return */
+	current->thread.fpu.fpc = vcpu->arch.host_fpregs.fpc;
+	current->thread.fpu.regs = vcpu->arch.host_fpregs.regs;
+	if (likely(!kvm_s390_pv_is_protected(vcpu->kvm)))
+		store_regs_fmt2(vcpu, kvm_run);
+}
+
 int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 {
 	int rc;
@@ -4585,6 +4608,9 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 	case KVM_SET_ONE_REG:
 	case KVM_GET_ONE_REG: {
 		struct kvm_one_reg reg;
+		r = -EINVAL;
+		if (kvm_s390_pv_is_protected(vcpu->kvm))
+			break;
 		r = -EFAULT;
 		if (copy_from_user(&reg, argp, sizeof(reg)))
 			break;
-- 
2.20.1
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