linux-kernel - [PATCH] RISCV: KVM: use raw_spinlock for critical section in imsic

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Message-Id: <20240919160126.44487-1-cyan.yang@sifive.com>
Date: Fri, 20 Sep 2024 00:01:26 +0800
From: Cyan Yang <cyan.yang@...ive.com>
To: anup@...infault.org
Cc: atishp@...shpatra.org,
	paul.walmsley@...ive.com,
	palmer@...belt.com,
	aou@...s.berkeley.edu,
	kvm@...r.kernel.org,
	kvm-riscv@...ts.infradead.org,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Cyan Yang <cyan.yang@...ive.com>,
	Yong-Xuan Wang <yongxuan.wang@...ive.com>
Subject: [PATCH] RISCV: KVM: use raw_spinlock for critical section in imsic

For the external interrupt updating procedure in imsic, there was a
spinlock to protect it already. But since it should not be preempted in
any cases, we should turn to use raw_spinlock to prevent any preemption
in case PREEMPT_RT was enabled.

Signed-off-by: Cyan Yang <cyan.yang@...ive.com>
Reviewed-by: Yong-Xuan Wang <yongxuan.wang@...ive.com>
---
 arch/riscv/kvm/aia_imsic.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/kvm/aia_imsic.c b/arch/riscv/kvm/aia_imsic.c
index 0a1e85932..a8085cd82 100644
--- a/arch/riscv/kvm/aia_imsic.c
+++ b/arch/riscv/kvm/aia_imsic.c
@@ -55,7 +55,7 @@ struct imsic {
 	/* IMSIC SW-file */
 	struct imsic_mrif *swfile;
 	phys_addr_t swfile_pa;
-	spinlock_t swfile_extirq_lock;
+	raw_spinlock_t swfile_extirq_lock;
 };
 
 #define imsic_vs_csr_read(__c)			\
@@ -622,7 +622,7 @@ static void imsic_swfile_extirq_update(struct kvm_vcpu *vcpu)
 	 * interruptions between reading topei and updating pending status.
 	 */
 
-	spin_lock_irqsave(&imsic->swfile_extirq_lock, flags);
+	raw_spin_lock_irqsave(&imsic->swfile_extirq_lock, flags);
 
 	if (imsic_mrif_atomic_read(mrif, &mrif->eidelivery) &&
 	    imsic_mrif_topei(mrif, imsic->nr_eix, imsic->nr_msis))
@@ -630,7 +630,7 @@ static void imsic_swfile_extirq_update(struct kvm_vcpu *vcpu)
 	else
 		kvm_riscv_vcpu_unset_interrupt(vcpu, IRQ_VS_EXT);
 
-	spin_unlock_irqrestore(&imsic->swfile_extirq_lock, flags);
+	raw_spin_unlock_irqrestore(&imsic->swfile_extirq_lock, flags);
 }
 
 static void imsic_swfile_read(struct kvm_vcpu *vcpu, bool clear,
@@ -1051,7 +1051,7 @@ int kvm_riscv_vcpu_aia_imsic_init(struct kvm_vcpu *vcpu)
 	}
 	imsic->swfile = page_to_virt(swfile_page);
 	imsic->swfile_pa = page_to_phys(swfile_page);
-	spin_lock_init(&imsic->swfile_extirq_lock);
+	raw_spin_lock_init(&imsic->swfile_extirq_lock);
 
 	/* Setup IO device */
 	kvm_iodevice_init(&imsic->iodev, &imsic_iodoev_ops);
-- 
2.39.5 (Apple Git-154)