[PATCH 0/6] KVM: s390: vsie: Small VSIE cleanup and improvements

[PATCH 0/6] KVM: s390: vsie: Small VSIE cleanup and improvements

[Christoph Schlameuss]

Some patches previously sent in series
"KVM: s390: vsie: Add VSIE SIGP Interpretation (vsie_sigpi) v1"

Link: https://lore.kernel.org/r/20260709-vsie-sigpi-v1-0-ea9f12066408@linux.ibm.com

now in its own series as proposed by Janosch in

Link: https://lore.kernel.org/all/77387525-cf7b-4617-a492-d81b6c1cef17@linux.ibm.com/

As well as some small additions like some of the offsets in struct
vsie_page do have in page offset or alignment requirements. Adding
assertions can actually prevent bad code changes as well as provide
clarity for the requirements.

And introduction of simple SCB_ALIGNMENT_SHIFT constant.

---
Christoph Schlameuss (6):
      KVM: s390: Remove double 64bscao feature check
      KVM: s390: vsie: Remove duplicate assertion
      KVM: s390: vsie: Convert shift to phys_to_pfn()
      KVM: s390: vsie: Assert mcck_info offset in vsie_page
      KVM: s390: vsie: Assert crycb alignment in vsie_page
      KVM: s390: vsie: Create constant SCB_ALIGNMENT_SHIFT

 arch/s390/include/asm/kvm_host_types.h |  2 ++
 arch/s390/kvm/kvm-s390.c               |  3 +--
 arch/s390/kvm/vsie.c                   | 19 +++++++++----------
 3 files changed, 12 insertions(+), 12 deletions(-)
---
base-commit: f9a2394a23482bfd330911e9c8295b71724feacd
change-id: 20260716-vsie-cleanup-202607-8690ba7ac3ea

Best regards,
-- 
Christoph Schlameuss <schlameuss@linux.ibm.com>

[PATCH 1/6] KVM: s390: Remove double 64bscao feature check

[Christoph Schlameuss]

sclp.has_64bscao is already verified in the guard clause a few lines
above this. So we cannot reach this code if it is not true.

Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
---
 arch/s390/kvm/kvm-s390.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 150b5dd2170e..c679d8f83c0e 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -455,8 +455,7 @@ static void __init kvm_s390_cpu_feat_init(void)
 	    !test_facility(3) || !nested)
 		return;
 	allow_cpu_feat(KVM_S390_VM_CPU_FEAT_SIEF2);
-	if (sclp.has_64bscao)
-		allow_cpu_feat(KVM_S390_VM_CPU_FEAT_64BSCAO);
+	allow_cpu_feat(KVM_S390_VM_CPU_FEAT_64BSCAO);
 	if (sclp.has_siif)
 		allow_cpu_feat(KVM_S390_VM_CPU_FEAT_SIIF);
 	if (sclp.has_gpere)

-- 
2.55.0

[PATCH 2/6] KVM: s390: vsie: Remove duplicate assertion

[Christoph Schlameuss]

This is covered by a static_assert at the struct vsie_page definition.

Fixes: e38c884df921 ("KVM: s390: Switch to new gmap")
Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
---
 arch/s390/kvm/vsie.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index eea24562e7db..3e956c7faa4b 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -1565,7 +1565,6 @@ int kvm_s390_handle_vsie(struct kvm_vcpu *vcpu)
 	if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
 		return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
 
-	BUILD_BUG_ON(sizeof(struct vsie_page) != PAGE_SIZE);
 	scb_addr = kvm_s390_get_base_disp_s(vcpu, NULL);
 
 	/* 512 byte alignment */

-- 
2.55.0

[PATCH 3/6] KVM: s390: vsie: Convert shift to phys_to_pfn()

[Christoph Schlameuss]

Make the code slightly more readable.

Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
---
 arch/s390/kvm/vsie.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 3e956c7faa4b..937f9c99bc00 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -701,7 +701,7 @@ static int pin_guest_page(struct kvm *kvm, gpa_t gpa, hpa_t *hpa)
 /* Unpins a page previously pinned via pin_guest_page, marking it as dirty. */
 static void unpin_guest_page(struct kvm *kvm, gpa_t gpa, hpa_t hpa)
 {
-	kvm_release_page_dirty(pfn_to_page(hpa >> PAGE_SHIFT));
+	kvm_release_page_dirty(pfn_to_page(phys_to_pfn(hpa)));
 	/* mark the page always as dirty for migration */
 	mark_page_dirty(kvm, gpa_to_gfn(gpa));
 }

-- 
2.55.0

[PATCH 4/6] KVM: s390: vsie: Assert mcck_info offset in vsie_page

[Christoph Schlameuss]

Ensure that the backup info for machine check is the same offset as that
in struct sie_page!

With the assertion in place we do not need the comment anymore.

Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
---
 arch/s390/kvm/vsie.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 937f9c99bc00..7c3b5e11b301 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -33,10 +33,7 @@ enum vsie_page_flags {
 
 struct vsie_page {
 	struct kvm_s390_sie_block scb_s;	/* 0x0000 */
-	/*
-	 * the backup info for machine check. ensure it's at
-	 * the same offset as that in struct sie_page!
-	 */
+	/* backup info for machine check */
 	struct mcck_volatile_info mcck_info;    /* 0x0200 */
 	/*
 	 * The pinned original scb. Be aware that other VCPUs can modify
@@ -71,6 +68,7 @@ struct vsie_page {
 };
 
 static_assert(sizeof(struct vsie_page) == PAGE_SIZE);
+static_assert(offsetof(struct vsie_page, mcck_info) == offsetof(struct sie_page, mcck_info));
 
 /* trigger a validity icpt for the given scb */
 static int set_validity_icpt(struct kvm_s390_sie_block *scb,

-- 
2.55.0

[PATCH 5/6] KVM: s390: vsie: Assert crycb alignment in vsie_page

[Christoph Schlameuss]

The crypto control block address is required to have double word
alignment.

Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
---
 arch/s390/kvm/vsie.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 7c3b5e11b301..c9392460edca 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -69,6 +69,7 @@ struct vsie_page {
 
 static_assert(sizeof(struct vsie_page) == PAGE_SIZE);
 static_assert(offsetof(struct vsie_page, mcck_info) == offsetof(struct sie_page, mcck_info));
+static_assert(IS_ALIGNED(offsetof(struct vsie_page, crycb), 8));
 
 /* trigger a validity icpt for the given scb */
 static int set_validity_icpt(struct kvm_s390_sie_block *scb,

-- 
2.55.0

[PATCH 6/6] KVM: s390: vsie: Create constant SCB_ALIGNMENT_SHIFT

[Christoph Schlameuss]

Create a simple constant for the SCB alignment shift.

Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
---
 arch/s390/include/asm/kvm_host_types.h | 2 ++
 arch/s390/kvm/vsie.c                   | 9 +++++----
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/s390/include/asm/kvm_host_types.h b/arch/s390/include/asm/kvm_host_types.h
index 3f50942bdfe6..ac82dd09fce5 100644
--- a/arch/s390/include/asm/kvm_host_types.h
+++ b/arch/s390/include/asm/kvm_host_types.h
@@ -9,6 +9,8 @@
 #define KVM_S390_BSCA_CPU_SLOTS 64
 #define KVM_S390_ESCA_CPU_SLOTS 248
 
+#define SCB_ALIGNMENT_SHIFT 9
+
 #define SIGP_CTRL_C		0x80
 #define SIGP_CTRL_SCN_MASK	0x3f
 
diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index c9392460edca..eb60a359d0aa 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -1485,7 +1485,7 @@ static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr)
 	int nr_vcpus;
 
 	rcu_read_lock();
-	vsie_page = radix_tree_lookup(&kvm->arch.vsie.addr_to_page, addr >> 9);
+	vsie_page = radix_tree_lookup(&kvm->arch.vsie.addr_to_page, addr >> SCB_ALIGNMENT_SHIFT);
 	rcu_read_unlock();
 	if (vsie_page) {
 		if (try_get_vsie_page(vsie_page)) {
@@ -1526,13 +1526,14 @@ static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr)
 		}
 		if (vsie_page->scb_gpa != ULONG_MAX)
 			radix_tree_delete(&kvm->arch.vsie.addr_to_page,
-					  vsie_page->scb_gpa >> 9);
+					  vsie_page->scb_gpa >> SCB_ALIGNMENT_SHIFT);
 	}
 	/* Mark it as invalid until it resides in the tree. */
 	vsie_page->scb_gpa = ULONG_MAX;
 
 	/* Double use of the same address or allocation failure. */
-	if (radix_tree_insert(&kvm->arch.vsie.addr_to_page, addr >> 9, vsie_page)) {
+	if (radix_tree_insert(&kvm->arch.vsie.addr_to_page, addr >> SCB_ALIGNMENT_SHIFT,
+			      vsie_page)) {
 		put_vsie_page(vsie_page);
 		mutex_unlock(&kvm->arch.vsie.mutex);
 		return NULL;
@@ -1630,7 +1631,7 @@ void kvm_s390_vsie_destroy(struct kvm *kvm)
 		/* free the radix tree entry */
 		if (vsie_page->scb_gpa != ULONG_MAX)
 			radix_tree_delete(&kvm->arch.vsie.addr_to_page,
-					  vsie_page->scb_gpa >> 9);
+					  vsie_page->scb_gpa >> SCB_ALIGNMENT_SHIFT);
 		free_page((unsigned long)vsie_page);
 	}
 	kvm->arch.vsie.page_count = 0;

-- 
2.55.0

Re: [PATCH 2/6] KVM: s390: vsie: Remove duplicate assertion

[sashiko-bot]

> This is covered by a static_assert at the struct vsie_page definition.
> 
> Fixes: e38c884df921 ("KVM: s390: Switch to new gmap")
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260807-vsie-cleanup-202607-v1-0-b18659b55e3d@linux.ibm.com?part=2

Re: [PATCH 1/6] KVM: s390: Remove double 64bscao feature check

[sashiko-bot]

> sclp.has_64bscao is already verified in the guard clause a few lines
> above this. So we cannot reach this code if it is not true.
> 
> Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
> Reviewed-by: Eric Farman <farman@linux.ibm.com>
> Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260807-vsie-cleanup-202607-v1-0-b18659b55e3d@linux.ibm.com?part=1

Re: [PATCH 5/6] KVM: s390: vsie: Assert crycb alignment in vsie_page

[sashiko-bot]

> The crypto control block address is required to have double word
> alignment.
> 
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260807-vsie-cleanup-202607-v1-0-b18659b55e3d@linux.ibm.com?part=5

Re: [PATCH 4/6] KVM: s390: vsie: Assert mcck_info offset in vsie_page

[sashiko-bot]

> Ensure that the backup info for machine check is the same offset as that
> in struct sie_page!
> 
> With the assertion in place we do not need the comment anymore.
> 
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260807-vsie-cleanup-202607-v1-0-b18659b55e3d@linux.ibm.com?part=4

Re: [PATCH 3/6] KVM: s390: vsie: Convert shift to phys_to_pfn()

[sashiko-bot]

> Make the code slightly more readable.
> 
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260807-vsie-cleanup-202607-v1-0-b18659b55e3d@linux.ibm.com?part=3

Re: [PATCH 6/6] KVM: s390: vsie: Create constant SCB_ALIGNMENT_SHIFT

[sashiko-bot]

> Create a simple constant for the SCB alignment shift.
> 
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260807-vsie-cleanup-202607-v1-0-b18659b55e3d@linux.ibm.com?part=6

Re: [PATCH 2/6] KVM: s390: vsie: Remove duplicate assertion

[Christian Borntraeger]

Am 07.08.26 um 11:57 schrieb Christoph Schlameuss:
> This is covered by a static_assert at the struct vsie_page definition.
> 
> Fixes: e38c884df921 ("KVM: s390: Switch to new gmap")

we could argue to remove this as this is likely not needed for stable
since its a build bug, but does not hurt.



> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
> ---
>   arch/s390/kvm/vsie.c | 1 -
>   1 file changed, 1 deletion(-)
> 
> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
> index eea24562e7db..3e956c7faa4b 100644
> --- a/arch/s390/kvm/vsie.c
> +++ b/arch/s390/kvm/vsie.c
> @@ -1565,7 +1565,6 @@ int kvm_s390_handle_vsie(struct kvm_vcpu *vcpu)
>   	if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
>   		return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
>   
> -	BUILD_BUG_ON(sizeof(struct vsie_page) != PAGE_SIZE);
>   	scb_addr = kvm_s390_get_base_disp_s(vcpu, NULL);
>   
>   	/* 512 byte alignment */
> 

Re: [PATCH 3/6] KVM: s390: vsie: Convert shift to phys_to_pfn()

[Christian Borntraeger]

Am 07.08.26 um 11:57 schrieb Christoph Schlameuss:
> Make the code slightly more readable.
> 
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>

Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>

> ---
>   arch/s390/kvm/vsie.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
> index 3e956c7faa4b..937f9c99bc00 100644
> --- a/arch/s390/kvm/vsie.c
> +++ b/arch/s390/kvm/vsie.c
> @@ -701,7 +701,7 @@ static int pin_guest_page(struct kvm *kvm, gpa_t gpa, hpa_t *hpa)
>   /* Unpins a page previously pinned via pin_guest_page, marking it as dirty. */
>   static void unpin_guest_page(struct kvm *kvm, gpa_t gpa, hpa_t hpa)
>   {
> -	kvm_release_page_dirty(pfn_to_page(hpa >> PAGE_SHIFT));
> +	kvm_release_page_dirty(pfn_to_page(phys_to_pfn(hpa)));
>   	/* mark the page always as dirty for migration */
>   	mark_page_dirty(kvm, gpa_to_gfn(gpa));
>   }
> 

Re: [PATCH 4/6] KVM: s390: vsie: Assert mcck_info offset in vsie_page

[Christian Borntraeger]

Am 07.08.26 um 11:57 schrieb Christoph Schlameuss:
> Ensure that the backup info for machine check is the same offset as that
> in struct sie_page!
> 
> With the assertion in place we do not need the comment anymore.

Nice and useful.

Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>> 
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
> ---
>   arch/s390/kvm/vsie.c | 6 ++----
>   1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
> index 937f9c99bc00..7c3b5e11b301 100644
> --- a/arch/s390/kvm/vsie.c
> +++ b/arch/s390/kvm/vsie.c
> @@ -33,10 +33,7 @@ enum vsie_page_flags {
>   
>   struct vsie_page {
>   	struct kvm_s390_sie_block scb_s;	/* 0x0000 */
> -	/*
> -	 * the backup info for machine check. ensure it's at
> -	 * the same offset as that in struct sie_page!
> -	 */
> +	/* backup info for machine check */
>   	struct mcck_volatile_info mcck_info;    /* 0x0200 */
>   	/*
>   	 * The pinned original scb. Be aware that other VCPUs can modify
> @@ -71,6 +68,7 @@ struct vsie_page {
>   };
>   
>   static_assert(sizeof(struct vsie_page) == PAGE_SIZE);
> +static_assert(offsetof(struct vsie_page, mcck_info) == offsetof(struct sie_page, mcck_info));
>   
>   /* trigger a validity icpt for the given scb */
>   static int set_validity_icpt(struct kvm_s390_sie_block *scb,
> 

Re: [PATCH 5/6] KVM: s390: vsie: Assert crycb alignment in vsie_page

[Christian Borntraeger]

Am 07.08.26 um 11:57 schrieb Christoph Schlameuss:
> The crypto control block address is required to have double word
> alignment.
> 
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>

Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>

> ---
>   arch/s390/kvm/vsie.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
> index 7c3b5e11b301..c9392460edca 100644
> --- a/arch/s390/kvm/vsie.c
> +++ b/arch/s390/kvm/vsie.c
> @@ -69,6 +69,7 @@ struct vsie_page {
>   
>   static_assert(sizeof(struct vsie_page) == PAGE_SIZE);
>   static_assert(offsetof(struct vsie_page, mcck_info) == offsetof(struct sie_page, mcck_info));
> +static_assert(IS_ALIGNED(offsetof(struct vsie_page, crycb), 8));
>   
>   /* trigger a validity icpt for the given scb */
>   static int set_validity_icpt(struct kvm_s390_sie_block *scb,
> 

Re: [PATCH 3/6] KVM: s390: vsie: Convert shift to phys_to_pfn()

[Sven Schnelle]

Christoph Schlameuss <schlameuss@linux.ibm.com> writes:

> Make the code slightly more readable.
>
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
> ---
>  arch/s390/kvm/vsie.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
> index 3e956c7faa4b..937f9c99bc00 100644
> --- a/arch/s390/kvm/vsie.c
> +++ b/arch/s390/kvm/vsie.c
> @@ -701,7 +701,7 @@ static int pin_guest_page(struct kvm *kvm, gpa_t gpa, hpa_t *hpa)
>  /* Unpins a page previously pinned via pin_guest_page, marking it as dirty. */
>  static void unpin_guest_page(struct kvm *kvm, gpa_t gpa, hpa_t hpa)
>  {
> -	kvm_release_page_dirty(pfn_to_page(hpa >> PAGE_SHIFT));
> +	kvm_release_page_dirty(pfn_to_page(phys_to_pfn(hpa)));
>  	/* mark the page always as dirty for migration */
>  	mark_page_dirty(kvm, gpa_to_gfn(gpa));
>  }

Could you add to the commit description what you changed? I.e. use
phys_to_pfn() instead of the open coded shift? It's bad if you do a 'git
log' and get commit with useless descriptions like 'make code more
readable'.

Re: [PATCH 1/6] KVM: s390: Remove double 64bscao feature check

[Claudio Imbrenda]

On Fri, 07 Aug 2026 11:57:42 +0200
Christoph Schlameuss <schlameuss@linux.ibm.com> wrote:

> sclp.has_64bscao is already verified in the guard clause a few lines
> above this. So we cannot reach this code if it is not true.
> 
> Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
> Reviewed-by: Eric Farman <farman@linux.ibm.com>
> Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

> ---
>  arch/s390/kvm/kvm-s390.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 150b5dd2170e..c679d8f83c0e 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -455,8 +455,7 @@ static void __init kvm_s390_cpu_feat_init(void)
>  	    !test_facility(3) || !nested)
>  		return;
>  	allow_cpu_feat(KVM_S390_VM_CPU_FEAT_SIEF2);
> -	if (sclp.has_64bscao)
> -		allow_cpu_feat(KVM_S390_VM_CPU_FEAT_64BSCAO);
> +	allow_cpu_feat(KVM_S390_VM_CPU_FEAT_64BSCAO);
>  	if (sclp.has_siif)
>  		allow_cpu_feat(KVM_S390_VM_CPU_FEAT_SIIF);
>  	if (sclp.has_gpere)
> 

Re: [PATCH 2/6] KVM: s390: vsie: Remove duplicate assertion

[Claudio Imbrenda]

On Fri, 07 Aug 2026 11:57:43 +0200
Christoph Schlameuss <schlameuss@linux.ibm.com> wrote:

Add this above:

"Remove useless BUILD_BUG_ON() checking the size of struct vsie_page."

and then this:

> This is covered by a static_assert at the struct vsie_page definition.
        ^^^
I would add "already" in there

> 
> Fixes: e38c884df921 ("KVM: s390: Switch to new gmap")
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
> ---
>  arch/s390/kvm/vsie.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
> index eea24562e7db..3e956c7faa4b 100644
> --- a/arch/s390/kvm/vsie.c
> +++ b/arch/s390/kvm/vsie.c
> @@ -1565,7 +1565,6 @@ int kvm_s390_handle_vsie(struct kvm_vcpu *vcpu)
>  	if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
>  		return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
>  
> -	BUILD_BUG_ON(sizeof(struct vsie_page) != PAGE_SIZE);
>  	scb_addr = kvm_s390_get_base_disp_s(vcpu, NULL);
>  
>  	/* 512 byte alignment */
> 

Re: [PATCH 3/6] KVM: s390: vsie: Convert shift to phys_to_pfn()

[Claudio Imbrenda]

On Fri, 07 Aug 2026 11:57:44 +0200
Christoph Schlameuss <schlameuss@linux.ibm.com> wrote:

> Make the code slightly more readable.

... "by using phys_to_pfn() instead of an open coded shift"

> 
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
> ---
>  arch/s390/kvm/vsie.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
> index 3e956c7faa4b..937f9c99bc00 100644
> --- a/arch/s390/kvm/vsie.c
> +++ b/arch/s390/kvm/vsie.c
> @@ -701,7 +701,7 @@ static int pin_guest_page(struct kvm *kvm, gpa_t gpa, hpa_t *hpa)
>  /* Unpins a page previously pinned via pin_guest_page, marking it as dirty. */
>  static void unpin_guest_page(struct kvm *kvm, gpa_t gpa, hpa_t hpa)
>  {
> -	kvm_release_page_dirty(pfn_to_page(hpa >> PAGE_SHIFT));
> +	kvm_release_page_dirty(pfn_to_page(phys_to_pfn(hpa)));
>  	/* mark the page always as dirty for migration */
>  	mark_page_dirty(kvm, gpa_to_gfn(gpa));
>  }
> 

Re: [PATCH 3/6] KVM: s390: vsie: Convert shift to phys_to_pfn()

[Sven Schnelle]

Sven Schnelle <svens@linux.ibm.com> writes:

> Christoph Schlameuss <schlameuss@linux.ibm.com> writes:
>
>> Make the code slightly more readable.
>>
>> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
>> ---
>>  arch/s390/kvm/vsie.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
>> index 3e956c7faa4b..937f9c99bc00 100644
>> --- a/arch/s390/kvm/vsie.c
>> +++ b/arch/s390/kvm/vsie.c
>> @@ -701,7 +701,7 @@ static int pin_guest_page(struct kvm *kvm, gpa_t gpa, hpa_t *hpa)
>>  /* Unpins a page previously pinned via pin_guest_page, marking it as dirty. */
>>  static void unpin_guest_page(struct kvm *kvm, gpa_t gpa, hpa_t hpa)
>>  {
>> -	kvm_release_page_dirty(pfn_to_page(hpa >> PAGE_SHIFT));
>> +	kvm_release_page_dirty(pfn_to_page(phys_to_pfn(hpa)));
>>  	/* mark the page always as dirty for migration */
>>  	mark_page_dirty(kvm, gpa_to_gfn(gpa));
>>  }
>
> Could you add to the commit description what you changed? I.e. use
> phys_to_pfn() instead of the open coded shift? It's bad if you do a 'git
> log' and get commit with useless descriptions like 'make code more
> readable'.

Nevermind - was in a rush and missed that it's in the summary... :-/

Re: [PATCH 5/6] KVM: s390: vsie: Assert crycb alignment in vsie_page

[Claudio Imbrenda]

On Fri, 07 Aug 2026 11:57:46 +0200
Christoph Schlameuss <schlameuss@linux.ibm.com> wrote:

> The crypto control block address is required to have double word
> alignment.

I would add:

"Add a static_assert to enforce correct alignment."

> 
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
> ---
>  arch/s390/kvm/vsie.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
> index 7c3b5e11b301..c9392460edca 100644
> --- a/arch/s390/kvm/vsie.c
> +++ b/arch/s390/kvm/vsie.c
> @@ -69,6 +69,7 @@ struct vsie_page {
>  
>  static_assert(sizeof(struct vsie_page) == PAGE_SIZE);
>  static_assert(offsetof(struct vsie_page, mcck_info) == offsetof(struct sie_page, mcck_info));
> +static_assert(IS_ALIGNED(offsetof(struct vsie_page, crycb), 8));
>  
>  /* trigger a validity icpt for the given scb */
>  static int set_validity_icpt(struct kvm_s390_sie_block *scb,
> 

Re: [PATCH 3/6] KVM: s390: vsie: Convert shift to phys_to_pfn()

[Claudio Imbrenda]

On Fri, 07 Aug 2026 13:06:41 +0200
Sven Schnelle <svens@linux.ibm.com> wrote:

> Sven Schnelle <svens@linux.ibm.com> writes:
> 
> > Christoph Schlameuss <schlameuss@linux.ibm.com> writes:
> >  
> >> Make the code slightly more readable.
> >>
> >> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
> >> ---
> >>  arch/s390/kvm/vsie.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
> >> index 3e956c7faa4b..937f9c99bc00 100644
> >> --- a/arch/s390/kvm/vsie.c
> >> +++ b/arch/s390/kvm/vsie.c
> >> @@ -701,7 +701,7 @@ static int pin_guest_page(struct kvm *kvm, gpa_t gpa, hpa_t *hpa)
> >>  /* Unpins a page previously pinned via pin_guest_page, marking it as dirty. */
> >>  static void unpin_guest_page(struct kvm *kvm, gpa_t gpa, hpa_t hpa)
> >>  {
> >> -	kvm_release_page_dirty(pfn_to_page(hpa >> PAGE_SHIFT));
> >> +	kvm_release_page_dirty(pfn_to_page(phys_to_pfn(hpa)));
> >>  	/* mark the page always as dirty for migration */
> >>  	mark_page_dirty(kvm, gpa_to_gfn(gpa));
> >>  }  
> >
> > Could you add to the commit description what you changed? I.e. use
> > phys_to_pfn() instead of the open coded shift? It's bad if you do a 'git
> > log' and get commit with useless descriptions like 'make code more
> > readable'.  
> 
> Nevermind - was in a rush and missed that it's in the summary... :-/

I still think the description should be self-contained and not be split
between the subject line and the body, even if it means that the body
of the text repeats the subject line again.

Re: [PATCH 0/6] KVM: s390: vsie: Small VSIE cleanup and improvements

[Christian Borntraeger]

Am 07.08.26 um 11:57 schrieb Christoph Schlameuss:
> Some patches previously sent in series
> "KVM: s390: vsie: Add VSIE SIGP Interpretation (vsie_sigpi) v1"
> 
> Link: https://lore.kernel.org/r/20260709-vsie-sigpi-v1-0-ea9f12066408@linux.ibm.com
> 
> now in its own series as proposed by Janosch in
> 
> Link: https://lore.kernel.org/all/77387525-cf7b-4617-a492-d81b6c1cef17@linux.ibm.com/
> 
> As well as some small additions like some of the offsets in struct
> vsie_page do have in page offset or alignment requirements. Adding
> assertions can actually prevent bad code changes as well as provide
> clarity for the requirements.
> 
> And introduction of simple SCB_ALIGNMENT_SHIFT constant.
> 
> ---
> Christoph Schlameuss (6):
>        KVM: s390: Remove double 64bscao feature check
>        KVM: s390: vsie: Remove duplicate assertion
>        KVM: s390: vsie: Convert shift to phys_to_pfn()
>        KVM: s390: vsie: Assert mcck_info offset in vsie_page
>        KVM: s390: vsie: Assert crycb alignment in vsie_page
>        KVM: s390: vsie: Create constant SCB_ALIGNMENT_SHIFT
> 
>   arch/s390/include/asm/kvm_host_types.h |  2 ++
>   arch/s390/kvm/kvm-s390.c               |  3 +--
>   arch/s390/kvm/vsie.c                   | 19 +++++++++----------
>   3 files changed, 12 insertions(+), 12 deletions(-)
> ---
> base-commit: f9a2394a23482bfd330911e9c8295b71724feacd
> change-id: 20260716-vsie-cleanup-202607-8690ba7ac3ea
> 
> Best regards,

I adjusted some commit messages and applied this series. Will schedule for next.

Re: [PATCH 0/6] KVM: s390: vsie: Small VSIE cleanup and improvements

[Christoph Schlameuss]

On Mon Aug 10, 2026 at 2:05 PM CEST, Christian Borntraeger wrote:
>
> Am 07.08.26 um 11:57 schrieb Christoph Schlameuss:
>> Some patches previously sent in series
>> "KVM: s390: vsie: Add VSIE SIGP Interpretation (vsie_sigpi) v1"
>> 
>> Link: https://lore.kernel.org/r/20260709-vsie-sigpi-v1-0-ea9f12066408@linux.ibm.com
>> 
>> now in its own series as proposed by Janosch in
>> 
>> Link: https://lore.kernel.org/all/77387525-cf7b-4617-a492-d81b6c1cef17@linux.ibm.com/
>> 
>> As well as some small additions like some of the offsets in struct
>> vsie_page do have in page offset or alignment requirements. Adding
>> assertions can actually prevent bad code changes as well as provide
>> clarity for the requirements.
>> 
>> And introduction of simple SCB_ALIGNMENT_SHIFT constant.
>> 
>> ---
>> Christoph Schlameuss (6):
>>        KVM: s390: Remove double 64bscao feature check
>>        KVM: s390: vsie: Remove duplicate assertion
>>        KVM: s390: vsie: Convert shift to phys_to_pfn()
>>        KVM: s390: vsie: Assert mcck_info offset in vsie_page
>>        KVM: s390: vsie: Assert crycb alignment in vsie_page
>>        KVM: s390: vsie: Create constant SCB_ALIGNMENT_SHIFT
>> 
>>   arch/s390/include/asm/kvm_host_types.h |  2 ++
>>   arch/s390/kvm/kvm-s390.c               |  3 +--
>>   arch/s390/kvm/vsie.c                   | 19 +++++++++----------
>>   3 files changed, 12 insertions(+), 12 deletions(-)
>> ---
>> base-commit: f9a2394a23482bfd330911e9c8295b71724feacd
>> change-id: 20260716-vsie-cleanup-202607-8690ba7ac3ea
>> 
>> Best regards,
>
> I adjusted some commit messages and applied this series. Will schedule for next.

Thanks!

(I did have the v2 ready, was just waiting if there where any more comments. But
it was only changes in the commit comments)