s390/entry: Pass the asce as parameter to sie64a()

Pass the guest ASCE explicitly as parameter, instead of having sie64a()
take it from lowcore.

This removes hidden state from lowcore, and makes things look cleaner.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Nico Boehr <nrb@linux.ibm.com>
Link: https://lore.kernel.org/r/20240703155900.103783-2-imbrenda@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

Author: Claudio Imbrenda

arch/s390/include/asm/kvm_host.h

@@ -1029,11 +1029,12 @@ void kvm_arch_crypto_clear_masks(struct kvm *kvm);
 void kvm_arch_crypto_set_masks(struct kvm *kvm, unsigned long *apm,
 			       unsigned long *aqm, unsigned long *adm);
 
-int __sie64a(phys_addr_t sie_block_phys, struct kvm_s390_sie_block *sie_block, u64 *rsa);
+int __sie64a(phys_addr_t sie_block_phys, struct kvm_s390_sie_block *sie_block, u64 *rsa,
+	     unsigned long gasce);
 
-static inline int sie64a(struct kvm_s390_sie_block *sie_block, u64 *rsa)
+static inline int sie64a(struct kvm_s390_sie_block *sie_block, u64 *rsa, unsigned long gasce)
 {
-	return __sie64a(virt_to_phys(sie_block), sie_block, rsa);
+	return __sie64a(virt_to_phys(sie_block), sie_block, rsa, gasce);
 }
 
 extern char sie_exit;

arch/s390/include/asm/stacktrace.h

@@ -65,6 +65,7 @@ struct stack_frame {
 			unsigned long sie_reason;
 			unsigned long sie_flags;
 			unsigned long sie_control_block_phys;
+			unsigned long sie_guest_asce;
 		};
 	};
 	unsigned long gprs[10];

arch/s390/kernel/asm-offsets.c

@@ -63,6 +63,7 @@ int main(void)
 	OFFSET(__SF_SIE_REASON, stack_frame, sie_reason);
 	OFFSET(__SF_SIE_FLAGS, stack_frame, sie_flags);
 	OFFSET(__SF_SIE_CONTROL_PHYS, stack_frame, sie_control_block_phys);
+	OFFSET(__SF_SIE_GUEST_ASCE, stack_frame, sie_guest_asce);
 	DEFINE(STACK_FRAME_OVERHEAD, sizeof(struct stack_frame));
 	BLANK();
 	OFFSET(__SFUSER_BACKCHAIN, stack_frame_user, back_chain);

arch/s390/kernel/entry.S

@@ -179,22 +179,20 @@ SYM_FUNC_END(__switch_to_asm)
  * %r2 pointer to sie control block phys
  * %r3 pointer to sie control block virt
  * %r4 guest register save area
+ * %r5 guest asce
  */
 SYM_FUNC_START(__sie64a)
 	stmg	%r6,%r14,__SF_GPRS(%r15)	# save kernel registers
 	lg	%r12,__LC_CURRENT
 	stg	%r2,__SF_SIE_CONTROL_PHYS(%r15)	# save sie block physical..
 	stg	%r3,__SF_SIE_CONTROL(%r15)	# ...and virtual addresses
 	stg	%r4,__SF_SIE_SAVEAREA(%r15)	# save guest register save area
+	stg	%r5,__SF_SIE_GUEST_ASCE(%r15)	# save guest asce
 	xc	__SF_SIE_REASON(8,%r15),__SF_SIE_REASON(%r15) # reason code = 0
 	mvc	__SF_SIE_FLAGS(8,%r15),__TI_flags(%r12) # copy thread flags
 	lmg	%r0,%r13,0(%r4)			# load guest gprs 0-13
-	lg	%r14,__LC_GMAP			# get gmap pointer
-	ltgr	%r14,%r14
-	jz	.Lsie_gmap
 	oi	__LC_CPU_FLAGS+7,_CIF_SIE
-	lctlg	%c1,%c1,__GMAP_ASCE(%r14)	# load primary asce
-.Lsie_gmap:
+	lctlg	%c1,%c1,__SF_SIE_GUEST_ASCE(%r15) # load primary asce
 	lg	%r14,__SF_SIE_CONTROL(%r15)	# get control block pointer
 	oi	__SIE_PROG0C+3(%r14),1		# we are going into SIE now
 	tm	__SIE_PROG20+3(%r14),3		# last exit...

arch/s390/kvm/kvm-s390.c

@@ -4829,7 +4829,8 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
 			       sizeof(sie_page->pv_grregs));
 		}
 		exit_reason = sie64a(vcpu->arch.sie_block,
-				     vcpu->run->s.regs.gprs);
+				     vcpu->run->s.regs.gprs,
+				     gmap_get_enabled()->asce);
 		if (kvm_s390_pv_cpu_is_protected(vcpu)) {
 			memcpy(vcpu->run->s.regs.gprs,
 			       sie_page->pv_grregs,

arch/s390/kvm/vsie.c

@@ -1150,7 +1150,7 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 	vcpu->arch.sie_block->prog0c |= PROG_IN_SIE;
 	barrier();
 	if (!kvm_s390_vcpu_sie_inhibited(vcpu))
-		rc = sie64a(scb_s, vcpu->run->s.regs.gprs);
+		rc = sie64a(scb_s, vcpu->run->s.regs.gprs, gmap_get_enabled()->asce);
 	barrier();
 	vcpu->arch.sie_block->prog0c &= ~PROG_IN_SIE;