linux-kernel - Re: [PATCH v3 06/11] s390/kvm: Stop using gmap

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Message-ID: <20241021095006.6950-B-hca@linux.ibm.com>
Date: Mon, 21 Oct 2024 11:50:06 +0200
From: Heiko Carstens <hca@...ux.ibm.com>
To: Claudio Imbrenda <imbrenda@...ux.ibm.com>
Cc: linux-kernel@...r.kernel.org, borntraeger@...ibm.com, nsg@...ux.ibm.com,
        nrb@...ux.ibm.com, frankja@...ux.ibm.com, seiden@...ux.ibm.com,
        agordeev@...ux.ibm.com, gor@...ux.ibm.com,
        gerald.schaefer@...ux.ibm.com, kvm@...r.kernel.org,
        linux-s390@...r.kernel.org
Subject: Re: [PATCH v3 06/11] s390/kvm: Stop using gmap_{en,dis}able()

On Tue, Oct 15, 2024 at 06:43:21PM +0200, Claudio Imbrenda wrote:
> Stop using gmap_enable(), gmap_disable(), gmap_get_enabled().
> 
> The correct guest ASCE is passed as a parameter of sie64a(), there is
> no need to save the current gmap in lowcore.
> 
> Signed-off-by: Claudio Imbrenda <imbrenda@...ux.ibm.com>
> Acked-by: Steffen Eiden <seiden@...ux.ibm.com>
> ---
>  arch/s390/kvm/kvm-s390.c | 7 +------
>  arch/s390/kvm/vsie.c     | 4 +---
>  2 files changed, 2 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index cfe3f8182aa5..df778a4a011d 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -3719,7 +3719,6 @@ __u64 kvm_s390_get_cpu_timer(struct kvm_vcpu *vcpu)
>  void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
>  {
>  
> -	gmap_enable(vcpu->arch.enabled_gmap);
>  	kvm_s390_set_cpuflags(vcpu, CPUSTAT_RUNNING);
>  	if (vcpu->arch.cputm_enabled && !is_vcpu_idle(vcpu))
>  		__start_cpu_timer_accounting(vcpu);
> @@ -3732,8 +3731,6 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
>  	if (vcpu->arch.cputm_enabled && !is_vcpu_idle(vcpu))
>  		__stop_cpu_timer_accounting(vcpu);
>  	kvm_s390_clear_cpuflags(vcpu, CPUSTAT_RUNNING);
> -	vcpu->arch.enabled_gmap = gmap_get_enabled();
> -	gmap_disable(vcpu->arch.enabled_gmap);

I guess you want to get rid of enabled_gmap as well, since it becomes
unused with this patch:

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 603b56bfccd3..51201b4ac93a 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -750,8 +750,6 @@ struct kvm_vcpu_arch {
 	struct hrtimer    ckc_timer;
 	struct kvm_s390_pgm_info pgm;
 	struct gmap *gmap;
-	/* backup location for the currently enabled gmap when scheduled out */
-	struct gmap *enabled_gmap;
 	struct kvm_guestdbg_info_arch guestdbg;
 	unsigned long pfault_token;
 	unsigned long pfault_select;

Reviewed-by: Heiko Carstens <hca@...ux.ibm.com>