FAILED: patch "[PATCH] KVM: x86: hyper-v: Don't auto-enable stimer on write from" failed to apply to 4.19-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.19-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-4.19.y
git checkout FETCH_HEAD
git cherry-pick -x d6800af51c76b6dae20e6023bbdc9b3da3ab5121
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2023112012-decency-frying-1e27@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..

Possible dependencies:

d6800af51c76 ("KVM: x86: hyper-v: Don't auto-enable stimer on write from user-space")
013cc6ebbf41 ("x86/kvm/hyper-v: avoid spurious pending stimer on vCPU init")
87a8d795b2f1 ("x86/hyper-v: Stop caring about EOI for direct stimers")
8644f771e07c ("x86/kvm/hyper-v: direct mode for synthetic timers")
6a058a1eadc3 ("x86/kvm/hyper-v: use stimer config definition from hyperv-tlfs.h")
0aa67255f54d ("x86/hyper-v: move synic/stimer control structures definitions to hyperv-tlfs.h")
7deec5e0df74 ("x86: kvm: hyperv: don't retry message delivery for periodic timers")
3a0e7731724f ("x86: kvm: hyperv: simplify SynIC message delivery")
f21dd494506a ("KVM: x86: hyperv: optimize sparse VP set processing")
e6b6c483ebe9 ("KVM: x86: hyperv: fix 'tlb_lush' typo")
214ff83d4473 ("KVM: x86: hyperv: implement PV IPI send hypercalls")
2cefc5feb80c ("KVM: x86: hyperv: optimize kvm_hv_flush_tlb() for vp_index == vcpu_idx case")
0b0a31badb2d ("KVM: x86: hyperv: valid_bank_mask should be 'u64'")
a812297c4fd9 ("KVM: x86: hyperv: optimize 'all cpus' case in kvm_hv_flush_tlb()")
aa069a996951 ("KVM: PPC: Book3S HV: Add a VM capability to enable nested virtualization")
9d67121a4fce ("Merge remote-tracking branch 'remotes/powerpc/topic/ppc-kvm' into kvm-ppc-next")

thanks,

greg k-h

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

From d6800af51c76b6dae20e6023bbdc9b3da3ab5121 Mon Sep 17 00:00:00 2001
From: Nicolas Saenz Julienne <nsaenz@amazon.com>
Date: Tue, 17 Oct 2023 15:51:02 +0000
Subject: [PATCH] KVM: x86: hyper-v: Don't auto-enable stimer on write from
 user-space

Don't apply the stimer's counter side effects when modifying its
value from user-space, as this may trigger spurious interrupts.

For example:
 - The stimer is configured in auto-enable mode.
 - The stimer's count is set and the timer enabled.
 - The stimer expires, an interrupt is injected.
 - The VM is live migrated.
 - The stimer config and count are deserialized, auto-enable is ON, the
   stimer is re-enabled.
 - The stimer expires right away, and injects an unwarranted interrupt.

Cc: stable@vger.kernel.org
Fixes: 1f4b34f825e8 ("kvm/x86: Hyper-V SynIC timers")
Signed-off-by: Nicolas Saenz Julienne <nsaenz@amazon.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20231017155101.40677-1-nsaenz@amazon.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 7c2dac6824e2..238afd7335e4 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -727,10 +727,12 @@ static int stimer_set_count(struct kvm_vcpu_hv_stimer *stimer, u64 count,
 
 	stimer_cleanup(stimer);
 	stimer->count = count;
-	if (stimer->count == 0)
-		stimer->config.enable = 0;
-	else if (stimer->config.auto_enable)
-		stimer->config.enable = 1;
+	if (!host) {
+		if (stimer->count == 0)
+			stimer->config.enable = 0;
+		else if (stimer->config.auto_enable)
+			stimer->config.enable = 1;
+	}
 
 	if (stimer->config.enable)
 		stimer_mark_pending(stimer, false);