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Message-Id: <20220302181143.188283-11-imbrenda@linux.ibm.com> Date: Wed, 2 Mar 2022 19:11:36 +0100 From: Claudio Imbrenda <imbrenda@...ux.ibm.com> To: kvm@...r.kernel.org Cc: borntraeger@...ibm.com, frankja@...ux.ibm.com, thuth@...hat.com, pasic@...ux.ibm.com, david@...hat.com, linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org, scgl@...ux.ibm.com, mimu@...ux.ibm.com, nrb@...ux.ibm.com Subject: [PATCH v8 10/17] KVM: s390: pv: add mmu_notifier Add an mmu_notifier for protected VMs. The callback function is triggered when the mm is torn down, and will attempt to convert all protected vCPUs to non-protected. This allows the mm teardown to use the destroy page UVC instead of export. Signed-off-by: Claudio Imbrenda <imbrenda@...ux.ibm.com> --- arch/s390/include/asm/kvm_host.h | 2 ++ arch/s390/kvm/kvm-s390.c | 5 ++++- arch/s390/kvm/pv.c | 26 ++++++++++++++++++++++++++ 3 files changed, 32 insertions(+), 1 deletion(-) diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h index a22c9266ea05..1bccb8561ba9 100644 --- a/arch/s390/include/asm/kvm_host.h +++ b/arch/s390/include/asm/kvm_host.h @@ -19,6 +19,7 @@ #include <linux/kvm.h> #include <linux/seqlock.h> #include <linux/module.h> +#include <linux/mmu_notifier.h> #include <asm/debug.h> #include <asm/cpu.h> #include <asm/fpu/api.h> @@ -921,6 +922,7 @@ struct kvm_s390_pv { u64 guest_len; unsigned long stor_base; void *stor_var; + struct mmu_notifier mmu_notifier; }; struct kvm_arch{ diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 21fcca09e9bf..446f89db93a1 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -32,6 +32,7 @@ #include <linux/sched/signal.h> #include <linux/string.h> #include <linux/pgtable.h> +#include <linux/mmu_notifier.h> #include <asm/asm-offsets.h> #include <asm/lowcore.h> @@ -2833,8 +2834,10 @@ void kvm_arch_destroy_vm(struct kvm *kvm) * can mess with the pv state. To avoid lockdep_assert_held from * complaining we do not use kvm_s390_pv_is_protected. */ - if (kvm_s390_pv_get_handle(kvm)) + if (kvm_s390_pv_get_handle(kvm)) { kvm_s390_pv_deinit_vm(kvm, &rc, &rrc); + mmu_notifier_unregister(&kvm->arch.pv.mmu_notifier, kvm->mm); + } debug_unregister(kvm->arch.dbf); free_page((unsigned long)kvm->arch.sie_page2); if (!kvm_is_ucontrol(kvm)) diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c index 76ef33a277d3..788b96b36931 100644 --- a/arch/s390/kvm/pv.c +++ b/arch/s390/kvm/pv.c @@ -14,6 +14,7 @@ #include <asm/mman.h> #include <linux/pagewalk.h> #include <linux/sched/mm.h> +#include <linux/mmu_notifier.h> #include "kvm-s390.h" static void kvm_s390_clear_pv_state(struct kvm *kvm) @@ -192,6 +193,26 @@ int kvm_s390_pv_deinit_vm(struct kvm *kvm, u16 *rc, u16 *rrc) return -EIO; } +static void kvm_s390_pv_mmu_notifier_release(struct mmu_notifier *subscription, + struct mm_struct *mm) +{ + struct kvm *kvm = container_of(subscription, struct kvm, arch.pv.mmu_notifier); + u16 dummy; + + /* + * No locking is needed since this is the last thread of the last user of this + * struct mm. + * When the struct kvm gets deinitialized, this notifier is also + * unregistered. This means that if this notifier runs, then the + * struct kvm is still valid. + */ + kvm_s390_cpus_from_pv(kvm, &dummy, &dummy); +} + +static const struct mmu_notifier_ops kvm_s390_pv_mmu_notifier_ops = { + .release = kvm_s390_pv_mmu_notifier_release, +}; + int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc) { struct uv_cb_cgc uvcb = { @@ -233,6 +254,11 @@ int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc) return -EIO; } kvm->arch.gmap->guest_handle = uvcb.guest_handle; + /* Add the notifier only once. No races because we hold kvm->lock */ + if (kvm->arch.pv.mmu_notifier.ops != &kvm_s390_pv_mmu_notifier_ops) { + kvm->arch.pv.mmu_notifier.ops = &kvm_s390_pv_mmu_notifier_ops; + mmu_notifier_register(&kvm->arch.pv.mmu_notifier, kvm->mm); + } return 0; } -- 2.34.1
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