FAILED: patch "[PATCH] KVM: SVM: Clear current_vmcb during vCPU free for all" failed to apply to 5.15-stable tree

FAILED: patch "[PATCH] KVM: SVM: Clear current_vmcb during vCPU free for all" failed to apply to 5.15-stable tree

[gregkh]

The patch below does not apply to the 5.15-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>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 1bee4838eb3a2c689f23c7170ea66ae87ea7d93a
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025062011-strained-factoid-f2fc@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

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

From 1bee4838eb3a2c689f23c7170ea66ae87ea7d93a Mon Sep 17 00:00:00 2001
From: Yosry Ahmed <yosry.ahmed@linux.dev>
Date: Tue, 29 Apr 2025 08:32:15 -0700
Subject: [PATCH] KVM: SVM: Clear current_vmcb during vCPU free for all
 *possible* CPUs

When freeing a vCPU and thus its VMCB, clear current_vmcb for all possible
CPUs, not just online CPUs, as it's theoretically possible a CPU could go
offline and come back online in conjunction with KVM reusing the page for
a new VMCB.

Link: https://lore.kernel.org/all/20250320013759.3965869-1-yosry.ahmed@linux.dev
Fixes: fd65d3142f73 ("kvm: svm: Ensure an IBPB on all affected CPUs when freeing a vmcb")
Cc: stable@vger.kernel.org
Cc: Jim Mattson <jmattson@google.com>
Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
[sean: split to separate patch, write changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 8eb482ca3359..e6802e33c54d 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1496,7 +1496,7 @@ static void svm_clear_current_vmcb(struct vmcb *vmcb)
 {
 	int i;
 
-	for_each_online_cpu(i)
+	for_each_possible_cpu(i)
 		cmpxchg(per_cpu_ptr(&svm_data.current_vmcb, i), vmcb, NULL);
 }