linux-kernel - [PATCH v12 12/18] KVM: s390: pv: destroy the configuration before its memory

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Message-Id: <20220628135619.32410-13-imbrenda@linux.ibm.com>
Date:   Tue, 28 Jun 2022 15:56:13 +0200
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 v12 12/18] KVM: s390: pv: destroy the configuration before its memory

Move the Destroy Secure Configuration UVC before the loop to destroy
the memory. If the protected VM has memory, it will be cleaned up and
made accessible by the Destroy Secure Configuration UVC. The struct
page for the relevant pages will still have the protected bit set, so
the loop is still needed to clean that up.

Switching the order of those two operations does not change the
outcome, but it is significantly faster.

Signed-off-by: Claudio Imbrenda <imbrenda@...ux.ibm.com>
Reviewed-by: Nico Boehr <nrb@...ux.ibm.com>
Reviewed-by: Janosch Frank <frankja@...ux.ibm.com>
---
 arch/s390/kvm/pv.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
index a389555d62e7..6cffea26c47f 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -163,6 +163,9 @@ int kvm_s390_pv_deinit_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
 {
 	int cc;
 
+	cc = uv_cmd_nodata(kvm_s390_pv_get_handle(kvm),
+			   UVC_CMD_DESTROY_SEC_CONF, rc, rrc);
+	WRITE_ONCE(kvm->arch.gmap->guest_handle, 0);
 	/*
 	 * if the mm still has a mapping, make all its pages accessible
 	 * before destroying the guest
@@ -172,9 +175,6 @@ int kvm_s390_pv_deinit_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
 		mmput(kvm->mm);
 	}
 
-	cc = uv_cmd_nodata(kvm_s390_pv_get_handle(kvm),
-			   UVC_CMD_DESTROY_SEC_CONF, rc, rrc);
-	WRITE_ONCE(kvm->arch.gmap->guest_handle, 0);
 	if (!cc) {
 		atomic_dec(&kvm->mm->context.protected_count);
 		kvm_s390_pv_dealloc_vm(kvm);
-- 
2.36.1