linux-kernel - [PATCH 5/5] KVM: RISC-V: reset smstateen CSRs

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Message-ID: <20250403112522.1566629-8-rkrcmar@ventanamicro.com>
Date: Thu,  3 Apr 2025 13:25:24 +0200
From: Radim Krčmář <rkrcmar@...tanamicro.com>
To: kvm-riscv@...ts.infradead.org
Cc: kvm@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Anup Patel <anup@...infault.org>,
	Atish Patra <atishp@...shpatra.org>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Alexandre Ghiti <alex@...ti.fr>,
	Andrew Jones <ajones@...tanamicro.com>,
	Mayuresh Chitale <mchitale@...tanamicro.com>
Subject: [PATCH 5/5] KVM: RISC-V: reset smstateen CSRs

Not resetting smstateen is a potential security hole, because VU might
be able to access state that VS does not properly context-switch.

Fixes: 81f0f314fec9 ("RISCV: KVM: Add sstateen0 context save/restore")
Signed-off-by: Radim Krčmář <rkrcmar@...tanamicro.com>
---
 arch/riscv/kvm/vcpu.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 4578863a39e3..ac0fa50bc489 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -65,6 +65,7 @@ static void kvm_riscv_vcpu_context_reset(struct kvm_vcpu *vcpu)
 
 	memset(cntx, 0, sizeof(*cntx));
 	memset(csr, 0, sizeof(*csr));
+	memset(&vcpu->arch.smstateen_csr, 0, sizeof(vcpu->arch.smstateen_csr));
 
 	/* Restore datap as it's not a part of the guest context. */
 	cntx->vector.datap = vector_datap;
-- 
2.48.1