FAILED: patch "[PATCH] KVM: arm64: Resolve all pending PC updates before immediate" failed to apply to 5.12-stable tree

FAILED: patch "[PATCH] KVM: arm64: Resolve all pending PC updates before immediate" failed to apply to 5.12-stable tree

[gregkh]

The patch below does not apply to the 5.12-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e3e880bb1518eb10a4b4bb4344ed614d6856f190 Mon Sep 17 00:00:00 2001
From: Zenghui Yu <yuzenghui@huawei.com>
Date: Wed, 26 May 2021 22:18:31 +0800
Subject: [PATCH] KVM: arm64: Resolve all pending PC updates before immediate
 exit

Commit 26778aaa134a ("KVM: arm64: Commit pending PC adjustemnts before
returning to userspace") fixed the PC updating issue by forcing an explicit
synchronisation of the exception state on vcpu exit to userspace.

However, we forgot to take into account the case where immediate_exit is
set by userspace and KVM_RUN will exit immediately. Fix it by resolving all
pending PC updates before returning to userspace.

Since __kvm_adjust_pc() relies on a loaded vcpu context, I moved the
immediate_exit checking right after vcpu_load(). We will get some overhead
if immediate_exit is true (which should hopefully be rare).

Fixes: 26778aaa134a ("KVM: arm64: Commit pending PC adjustemnts before returning to userspace")
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210526141831.1662-1-yuzenghui@huawei.com
Cc: stable@vger.kernel.org # 5.11

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 1126eae27400..e720148232a0 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -720,11 +720,13 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 			return ret;
 	}
 
-	if (run->immediate_exit)
-		return -EINTR;
-
 	vcpu_load(vcpu);
 
+	if (run->immediate_exit) {
+		ret = -EINTR;
+		goto out;
+	}
+
 	kvm_sigset_activate(vcpu);
 
 	ret = 1;
@@ -897,6 +899,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 
 	kvm_sigset_deactivate(vcpu);
 
+out:
 	/*
 	 * In the unlikely event that we are returning to userspace
 	 * with pending exceptions or PC adjustment, commit these