[PATCH 0/3] KVM: s390: arm64: Fixes for arm64 KVM support

[PATCH 0/3] KVM: s390: arm64: Fixes for arm64 KVM support

[Andreas Grapentin]

Some fixups for the previous series that introduced arm64 KVM support on
s390. Forward-declare enum vcpu_sysreg because we are definitely going
to need that, then make the module naming consistent and iron out an
inconsistency in the definition of vcpu->arch.pause between s390 and
native arm64 KVM.

No functional changes intended on either arm64 or s390.

Signed-off-by: Andreas Grapentin <gra@linux.ibm.com>
---
Andreas Grapentin (2):
      KVM: s390: arm64: Declare enum vcpu_sysreg
      KVM: s390: arm64: Fix kvm_arm64 module naming consistency

Steffen Eiden (1):
      KVM: s390: arm64: Turn vcpu->arch.pause into a counter

 arch/s390/include/asm/kvm_host_arm64.h |  8 ++++----
 arch/s390/kvm/arm64/Makefile           | 12 ++++++------
 2 files changed, 10 insertions(+), 10 deletions(-)
---
base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4
change-id: 20261103-s390_arm64_kvm_fixups-b285654f214c

Best regards,
-- 
Andreas Grapentin <gra@linux.ibm.com>

[PATCH 1/3] KVM: s390: arm64: Turn vcpu->arch.pause into a counter

[Andreas Grapentin]

From: Steffen Eiden <seiden@linux.ibm.com>

The s390 arm64 vcpu struct mirrors arm64's kvm_vcpu_arch. When commit
e64309198eda2 ("KVM: arm64: Turn vcpu->arch.pause into a counter")
changed the type of kvm_vcpu_arch.pause from bool to atomic_t, the merge
into this tree missed the s390 copy, leaving it out of sync.

Nothing on the s390 side accesses vcpu->arch.pause yet, so this has
no functional effect. Align the type to keep the mirror identical to
its arm64 counterpart.

Fixes: e6c329180d1d ("KVM: s390: arm64: Introduce host definitions")
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
Signed-off-by: Andreas Grapentin <gra@linux.ibm.com>
---
 arch/s390/include/asm/kvm_host_arm64.h | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/s390/include/asm/kvm_host_arm64.h b/arch/s390/include/asm/kvm_host_arm64.h
index 82343e723ebf..a3e40650d75d 100644
--- a/arch/s390/include/asm/kvm_host_arm64.h
+++ b/arch/s390/include/asm/kvm_host_arm64.h
@@ -63,11 +63,10 @@ struct kvm_vcpu_arch {
 	/*
 	 * Don't run the guest (internal implementation need).
 	 *
-	 * Contrary to the flags above, this is set/cleared outside of
-	 * a vcpu context, and thus cannot be mixed with the flags
-	 * themselves (or the flag accesses need to be made atomic).
+	 * Contrary to the flags above, this is updated outside of
+	 * a vcpu context, and thus cannot be mixed with the flags.
 	 */
-	bool pause;
+	atomic_t pause;
 
 	/* vcpu power state */
 	struct kvm_mp_state mp_state;

-- 
2.55.0

[PATCH 2/3] KVM: s390: arm64: Declare enum vcpu_sysreg

[Andreas Grapentin]

Forward-declare enum vcpu_sysreg in kvm_host_arm64.h. This should have
been included in the first iteration of the header, since we will need
it to talk about system registers.

Since the definition of enum vcpu_sysreg is not shared yet, and not used
on the s390 side, this should not cause any functional changes.

Fixes: e6c329180d1d ("KVM: s390: arm64: Introduce host definitions")
Signed-off-by: Andreas Grapentin <gra@linux.ibm.com>
---
 arch/s390/include/asm/kvm_host_arm64.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/s390/include/asm/kvm_host_arm64.h b/arch/s390/include/asm/kvm_host_arm64.h
index a3e40650d75d..3e69724f17c9 100644
--- a/arch/s390/include/asm/kvm_host_arm64.h
+++ b/arch/s390/include/asm/kvm_host_arm64.h
@@ -8,6 +8,7 @@
 #include <asm/debug.h>
 
 #define vcpu_gp_regs(v)		((v)->arch.sae_block.gpr)
+enum vcpu_sysreg;
 
 #include <arm64/kvm_host.h>
 #include <arm64/ptrace.h>

-- 
2.55.0

[PATCH 3/3] KVM: s390: arm64: Fix kvm_arm64 module naming consistency

[Andreas Grapentin]

the module build for the kvm_arm64 module produced kvm-arm64.ko, fix the
Makefile to produce kvm_arm64.ko instead, so the output file name
matches the module name.

Signed-off-by: Andreas Grapentin <gra@linux.ibm.com>
---
 arch/s390/kvm/arm64/Makefile | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/s390/kvm/arm64/Makefile b/arch/s390/kvm/arm64/Makefile
index 3f0fe5c9f0a1..b48dc65b7aaa 100644
--- a/arch/s390/kvm/arm64/Makefile
+++ b/arch/s390/kvm/arm64/Makefile
@@ -29,7 +29,7 @@ $(obj)/%-arm64.o: $(src)/%.c FORCE
 	$(call if_changed_rule,cc_o_c)
 	$(call cmd,force_checksrc)
 
-# %-arm64.o stems don't match any kvm-arm64-y entry so Kbuild derives wrong
+# %-arm64.o stems don't match any kvm_arm64-y entry so Kbuild derives wrong
 # KBUILD_MODNAME/KBUILD_MODFILE. Force include a generated header to override.
 KVM_ARM64_MODNAME_H := $(obj)/generated/kvm_arm64_modname.h
 ccflags-y += -include $(KVM_ARM64_MODNAME_H)
@@ -48,7 +48,7 @@ define filechk_kvm_arm64_modname
 	echo '#undef __KBUILD_MODNAME';				\
 	echo '#define __KBUILD_MODNAME $(KVM_DEV_NAME)';	\
 	echo '#undef KBUILD_MODFILE';				\
-	echo '#define KBUILD_MODFILE "$(obj)/kvm-arm64"';	\
+	echo '#define KBUILD_MODFILE "$(obj)/kvm_arm64"';	\
 	echo '#endif /* __KVM_ARM64_MODNAME_H */'
 endef
 
@@ -60,7 +60,7 @@ $(addprefix $(obj)/,$(kvm-arm64-obj)): private part-of-builtin := y
 
 ifeq ($(CONFIG_KVM),m)
 
-kvm-arm64-y = $(kvm-arm64-obj)
+kvm_arm64-y = $(kvm-arm64-obj)
 
 else ifeq ($(CONFIG_KVM),y)
 
@@ -86,7 +86,7 @@ $(obj)/kvm_symbol_list: $(obj)/kvm-unnamespaced.o FORCE
 
 # cmd_oc_o_o carries -DKBUILD_MODFILE so generate_builtin_ranges.awk
 # can attribute kvm-namespaced.o to kvm_arm64 via its .cmd file.
-cmd_oc_o_o = $(cmd_objcopy) -DKBUILD_MODFILE='"$(obj)/kvm-arm64"'
+cmd_oc_o_o = $(cmd_objcopy) -DKBUILD_MODFILE='"$(obj)/kvm_arm64"'
 define rule_oc_o_o
 	$(call cmd,objcopy)
 	@printf '%s\n' 'savedcmd_$@ := $(call make-cmd,oc_o_o)' > $(dot-target).cmd
@@ -98,7 +98,7 @@ OBJCOPYFLAGS_kvm-namespaced.o := -O $(LD_BFD) --localize-symbols=$(obj)/kvm_symb
 $(obj)/kvm-namespaced.o: $(obj)/kvm-unnamespaced.o $(obj)/kvm_symbol_list FORCE
 	$(call if_changed_rule,oc_o_o)
 
-kvm-arm64-y = kvm-namespaced.o
+kvm_arm64-y = kvm-namespaced.o
 
 targets += kvm-unnamespaced.o kvm_symbol_list kvm-namespaced.o
 
@@ -106,5 +106,5 @@ endif
 
 clean-files += kvm-unnamespaced.o kvm_symbol_list kvm-namespaced.o
 
-obj-$(CONFIG_KVM) += kvm-arm64.o
+obj-$(CONFIG_KVM) += kvm_arm64.o
 

-- 
2.55.0

Re: [PATCH 0/3] KVM: s390: arm64: Fixes for arm64 KVM support

[Marc Zyngier]

On Tue, 03 Nov 2026 16:37:01 +0000,
Andreas Grapentin <gra@linux.ibm.com> wrote:
> 
> Some fixups for the previous series that introduced arm64 KVM support on
> s390. Forward-declare enum vcpu_sysreg because we are definitely going
> to need that, then make the module naming consistent and iron out an
> inconsistency in the definition of vcpu->arch.pause between s390 and
> native arm64 KVM.

It's an interesting one. Obviously, this wasn't caught by building the
upstream code. I guess this triggered with the rest of the patches?

> 
> No functional changes intended on either arm64 or s390.
> 
> Signed-off-by: Andreas Grapentin <gra@linux.ibm.com>
> ---
> Andreas Grapentin (2):
>       KVM: s390: arm64: Declare enum vcpu_sysreg
>       KVM: s390: arm64: Fix kvm_arm64 module naming consistency
> 
> Steffen Eiden (1):
>       KVM: s390: arm64: Turn vcpu->arch.pause into a counter
> 
>  arch/s390/include/asm/kvm_host_arm64.h |  8 ++++----
>  arch/s390/kvm/arm64/Makefile           | 12 ++++++------
>  2 files changed, 10 insertions(+), 10 deletions(-)

Looks all reasonable to me.

Acked-by: Marc Zyngier <maz@kernel.org>

	M.

-- 
Without deviation from the norm, progress is not possible.