Re: [PATCH 5/7] KVM: s390: Replace KVM_REQ_MMU_RELOAD usage with arch specific request

Claudio Imbrenda
2021-12-09T09:20:36Z

On Thu, 9 Dec 2021 06:05:50 +0000
Sean Christopherson <seanjc@google.com> wrote:

> Add an arch request, KVM_REQ_REFRESH_GUEST_PREFIX, to deal with guest
> prefix changes instead of piggybacking KVM_REQ_MMU_RELOAD. This will
> allow for the removal of the generic KVM_REQ_MMU_RELOAD, which isn't
> actually used by generic KVM.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>

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

> ---
> arch/s390/include/asm/kvm_host.h | 2 ++
> arch/s390/kvm/kvm-s390.c | 8 ++++----
> arch/s390/kvm/kvm-s390.h | 2 +-
> 3 files changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
> index a22c9266ea05..766028d54a3e 100644
> --- a/arch/s390/include/asm/kvm_host.h
> +++ b/arch/s390/include/asm/kvm_host.h
> @@ -45,6 +45,8 @@
> #define KVM_REQ_START_MIGRATION KVM_ARCH_REQ(3)
> #define KVM_REQ_STOP_MIGRATION KVM_ARCH_REQ(4)
> #define KVM_REQ_VSIE_RESTART KVM_ARCH_REQ(5)
> +#define KVM_REQ_REFRESH_GUEST_PREFIX \
> + KVM_ARCH_REQ_FLAGS(6, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
>
> #define SIGP_CTRL_C 0x80
> #define SIGP_CTRL_SCN_MASK 0x3f
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index dd099d352753..e161df69520c 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -3394,7 +3394,7 @@ static void kvm_gmap_notifier(struct gmap *gmap, unsigned long start,
> if (prefix <= end && start <= prefix + 2*PAGE_SIZE - 1) {
> VCPU_EVENT(vcpu, 2, "gmap notifier for %lx-%lx",
> start, end);
> - kvm_s390_sync_request(KVM_REQ_MMU_RELOAD, vcpu);
> + kvm_s390_sync_request(KVM_REQ_REFRESH_GUEST_PREFIX, vcpu);
> }
> }
> }
> @@ -3796,19 +3796,19 @@ static int kvm_s390_handle_requests(struct kvm_vcpu *vcpu)
> if (!kvm_request_pending(vcpu))
> return 0;
> /*
> - * We use MMU_RELOAD just to re-arm the ipte notifier for the
> + * If the guest prefix changed, re-arm the ipte notifier for the
> * guest prefix page. gmap_mprotect_notify will wait on the ptl lock.
> * This ensures that the ipte instruction for this request has
> * already finished. We might race against a second unmapper that
> * wants to set the blocking bit. Lets just retry the request loop.
> */
> - if (kvm_check_request(KVM_REQ_MMU_RELOAD, vcpu)) {
> + if (kvm_check_request(KVM_REQ_REFRESH_GUEST_PREFIX, vcpu)) {
> int rc;
> rc = gmap_mprotect_notify(vcpu->arch.gmap,
> kvm_s390_get_prefix(vcpu),
> PAGE_SIZE * 2, PROT_WRITE);
> if (rc) {
> - kvm_make_request(KVM_REQ_MMU_RELOAD, vcpu);
> + kvm_make_request(KVM_REQ_REFRESH_GUEST_PREFIX, vcpu);
> return rc;
> }
> goto retry;
> diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
> index 60f0effcce99..219f92ffd556 100644
> --- a/arch/s390/kvm/kvm-s390.h
> +++ b/arch/s390/kvm/kvm-s390.h
> @@ -105,7 +105,7 @@ static inline void kvm_s390_set_prefix(struct kvm_vcpu *vcpu, u32 prefix)
> prefix);
> vcpu->arch.sie_block->prefix = prefix >> GUEST_PREFIX_SHIFT;
> kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
> - kvm_make_request(KVM_REQ_MMU_RELOAD, vcpu);
> + kvm_make_request(KVM_REQ_REFRESH_GUEST_PREFIX, vcpu);
> }
>
> static inline u64 kvm_s390_get_base_disp_s(struct kvm_vcpu *vcpu, u8 *ar)