linux-kernel - [PATCH 16/27] RISC-V: KVM: Check and inject nested virtual interrupts

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Message-ID: <20260120080013.2153519-17-anup.patel@oss.qualcomm.com>
Date: Tue, 20 Jan 2026 13:30:02 +0530
From: Anup Patel <anup.patel@....qualcomm.com>
To: Paolo Bonzini <pbonzini@...hat.com>, Atish Patra <atish.patra@...ux.dev>
Cc: Palmer Dabbelt <palmer@...belt.com>, Paul Walmsley <pjw@...nel.org>,
        Alexandre Ghiti <alex@...ti.fr>, Shuah Khan <shuah@...nel.org>,
        Anup Patel <anup@...infault.org>,
        Andrew Jones <andrew.jones@....qualcomm.com>,
        kvm-riscv@...ts.infradead.org, kvm@...r.kernel.org,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org,
        Anup Patel <anup.patel@....qualcomm.com>
Subject: [PATCH 16/27] RISC-V: KVM: Check and inject nested virtual interrupts

When entering guest in virtual-VS/VU mode (aka nested guest),
check and inject nested virtual interrupt right before guest
entry.

Signed-off-by: Anup Patel <anup.patel@....qualcomm.com>
---
 arch/riscv/include/asm/kvm_vcpu_nested.h |  1 +
 arch/riscv/kvm/vcpu.c                    |  3 ++
 arch/riscv/kvm/vcpu_nested.c             | 49 ++++++++++++++++++++++++
 3 files changed, 53 insertions(+)

diff --git a/arch/riscv/include/asm/kvm_vcpu_nested.h b/arch/riscv/include/asm/kvm_vcpu_nested.h
index 6bfb67702610..6d9d252a378c 100644
--- a/arch/riscv/include/asm/kvm_vcpu_nested.h
+++ b/arch/riscv/include/asm/kvm_vcpu_nested.h
@@ -86,6 +86,7 @@ void kvm_riscv_vcpu_nested_set_virt(struct kvm_vcpu *vcpu,
 void kvm_riscv_vcpu_nested_trap_redirect(struct kvm_vcpu *vcpu,
 					 struct kvm_cpu_trap *trap,
 					 bool prev_priv);
+void kvm_riscv_vcpu_nested_vsirq_process(struct kvm_vcpu *vcpu);
 
 void kvm_riscv_vcpu_nested_reset(struct kvm_vcpu *vcpu);
 int kvm_riscv_vcpu_nested_init(struct kvm_vcpu *vcpu);
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 077637aff9a2..f8c4344c2b1f 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -934,6 +934,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 		 */
 		kvm_riscv_local_tlb_sanitize(vcpu);
 
+		/* Check and inject nested virtual interrupts */
+		kvm_riscv_vcpu_nested_vsirq_process(vcpu);
+
 		trace_kvm_entry(vcpu);
 
 		guest_timing_enter_irqoff();
diff --git a/arch/riscv/kvm/vcpu_nested.c b/arch/riscv/kvm/vcpu_nested.c
index 214206fc28bb..9b2b3369a232 100644
--- a/arch/riscv/kvm/vcpu_nested.c
+++ b/arch/riscv/kvm/vcpu_nested.c
@@ -172,6 +172,55 @@ void kvm_riscv_vcpu_nested_trap_redirect(struct kvm_vcpu *vcpu,
 				       false, prev_priv, gva);
 }
 
+void kvm_riscv_vcpu_nested_vsirq_process(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu_nested *ns = &vcpu->arch.nested;
+	struct kvm_vcpu_nested_csr *nsc = &ns->csr;
+	struct kvm_cpu_trap trap;
+	unsigned long irqs;
+	bool next_spp;
+	int vsirq;
+
+	/* Do nothing if nested virtualization is OFF */
+	if (!ns->virt)
+		return;
+
+	/* Determine the virtual-VS mode interrupt number */
+	vsirq = 0;
+	irqs = nsc->hvip;
+	irqs &= nsc->vsie << VSIP_TO_HVIP_SHIFT;
+	irqs &= nsc->hideleg;
+	if (irqs & BIT(IRQ_VS_EXT))
+		vsirq = IRQ_S_EXT;
+	else if (irqs & BIT(IRQ_VS_TIMER))
+		vsirq = IRQ_S_TIMER;
+	else if (irqs & BIT(IRQ_VS_SOFT))
+		vsirq = IRQ_S_SOFT;
+	if (vsirq <= 0)
+		return;
+
+	/*
+	 * Determine whether we are resuming in virtual-VS mode
+	 * or virtual-VU mode.
+	 */
+	next_spp = !!(vcpu->arch.guest_context.sstatus & SR_SPP);
+
+	/*
+	 * If we are going to virtual-VS mode and interrupts are
+	 * disabled then do nothing.
+	 */
+	if (next_spp && !(ncsr_read(CSR_VSSTATUS) & SR_SIE))
+		return;
+
+	/* Take virtual-VS mode interrupt */
+	trap.scause = CAUSE_IRQ_FLAG | vsirq;
+	trap.sepc = vcpu->arch.guest_context.sepc;
+	trap.stval = 0;
+	trap.htval = 0;
+	trap.htinst = 0;
+	kvm_riscv_vcpu_trap_smode_redirect(vcpu, &trap, next_spp);
+}
+
 void kvm_riscv_vcpu_nested_reset(struct kvm_vcpu *vcpu)
 {
 	struct kvm_vcpu_nested *ns = &vcpu->arch.nested;
-- 
2.43.0