linux-kernel - Re: [PATCH v1 1/3] KVM: s390: Use guest address to mark guest page dirty

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Message-ID: <f5c07226-f748-46c9-a59b-e31494a5524f@linux.ibm.com>
Date: Fri, 6 Feb 2026 15:56:18 +0100
From: Janosch Frank <frankja@...ux.ibm.com>
To: Claudio Imbrenda <imbrenda@...ux.ibm.com>, kvm@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
        borntraeger@...ibm.com, nsg@...ux.ibm.com, nrb@...ux.ibm.com,
        seiden@...ux.ibm.com, gra@...ux.ibm.com, schlameuss@...ux.ibm.com,
        hca@...ux.ibm.com, svens@...ux.ibm.com, agordeev@...ux.ibm.com,
        gor@...ux.ibm.com, david@...nel.org, gerald.schaefer@...ux.ibm.com
Subject: Re: [PATCH v1 1/3] KVM: s390: Use guest address to mark guest page
 dirty

On 2/6/26 15:35, Claudio Imbrenda wrote:
> Stop using the userspace address to mark the guest page dirty.
> mark_page_dirty() expects a guest frame number, but was being passed a
> host virtual frame number. When slot == NULL, mark_page_dirty_in_slot()
> does nothing and does not complain.
> 
> This means that in some circumstances the dirtiness of the guest page
> might have been lost.
> 
> Fix by adding two fields in struct kvm_s390_adapter_int to keep the
> guest addressses, and use those for mark_page_dirty().
> 
> Fixes: f65470661f36 ("KVM: s390/interrupt: do not pin adapter interrupt pages")
> Signed-off-by: Claudio Imbrenda <imbrenda@...ux.ibm.com>

Ouff
Reviewed-by: Janosch Frank <frankja@...ux.ibm.com>


We had so many of these issues and I wonder if we should move away from 
making everything u64 and enforce type checks in some form.

> ---
>   arch/s390/kvm/interrupt.c | 6 ++++--
>   include/linux/kvm_host.h  | 2 ++
>   2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> index f55eca9aa638..1c2bb5cd7e12 100644
> --- a/arch/s390/kvm/interrupt.c
> +++ b/arch/s390/kvm/interrupt.c
> @@ -2768,13 +2768,13 @@ static int adapter_indicators_set(struct kvm *kvm,
>   	bit = get_ind_bit(adapter_int->ind_addr,
>   			  adapter_int->ind_offset, adapter->swap);
>   	set_bit(bit, map);
> -	mark_page_dirty(kvm, adapter_int->ind_addr >> PAGE_SHIFT);
> +	mark_page_dirty(kvm, adapter_int->ind_gaddr >> PAGE_SHIFT);
>   	set_page_dirty_lock(ind_page);
>   	map = page_address(summary_page);
>   	bit = get_ind_bit(adapter_int->summary_addr,
>   			  adapter_int->summary_offset, adapter->swap);
>   	summary_set = test_and_set_bit(bit, map);
> -	mark_page_dirty(kvm, adapter_int->summary_addr >> PAGE_SHIFT);
> +	mark_page_dirty(kvm, adapter_int->summary_gaddr >> PAGE_SHIFT);
>   	set_page_dirty_lock(summary_page);
>   	srcu_read_unlock(&kvm->srcu, idx);
>   
> @@ -2870,7 +2870,9 @@ int kvm_set_routing_entry(struct kvm *kvm,
>   		if (kvm_is_error_hva(uaddr_s) || kvm_is_error_hva(uaddr_i))
>   			return -EFAULT;
>   		e->adapter.summary_addr = uaddr_s;
> +		e->adapter.summary_gaddr = ue->u.adapter.summary_addr;
>   		e->adapter.ind_addr = uaddr_i;
> +		e->adapter.ind_gaddr = ue->u.adapter.ind_addr;
>   		e->adapter.summary_offset = ue->u.adapter.summary_offset;
>   		e->adapter.ind_offset = ue->u.adapter.ind_offset;
>   		e->adapter.adapter_id = ue->u.adapter.adapter_id;
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index d93f75b05ae2..deb36007480d 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -645,7 +645,9 @@ static inline unsigned long *kvm_second_dirty_bitmap(struct kvm_memory_slot *mem
>   
>   struct kvm_s390_adapter_int {
>   	u64 ind_addr;
> +	u64 ind_gaddr;
>   	u64 summary_addr;
> +	u64 summary_gaddr;
>   	u64 ind_offset;
>   	u32 summary_offset;
>   	u32 adapter_id;