linux-kernel - [PATCH v10 13/19] KVM: s390: pv: destroy the configuration before its memory

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Message-Id: <20220414080311.1084834-14-imbrenda@linux.ibm.com>
Date:   Thu, 14 Apr 2022 10:03:04 +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 v10 13/19] 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 Configuraion 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>
---
 arch/s390/kvm/pv.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
index be3b467f8feb..bd850be08c86 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -168,6 +168,8 @@ 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);
 	/*
 	 * if the mm still has a mapping, make all its pages accessible
 	 * before destroying the guest
@@ -177,8 +179,6 @@ 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);
-- 
2.34.1