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

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Message-ID: <CAAhSdy0+C34zZbYR3_B9x6xHihwfLxeTBOfrdRfLRjFUN=78gA@mail.gmail.com>
Date: Fri, 25 Apr 2025 18:08:32 +0530
From: Anup Patel <anup@...infault.org>
To: Radim Krčmář <rkrcmar@...tanamicro.com>
Cc: kvm-riscv@...ts.infradead.org, kvm@...r.kernel.org, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.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: Re: [PATCH 5/5] KVM: RISC-V: reset smstateen CSRs

On Thu, Apr 3, 2025 at 5:02 PM Radim Krčmář <rkrcmar@...tanamicro.com> wrote:
>
> 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>

This should be the first patch of the series which can
be applied independently.

I have rebased and queued it as a fix for Linux-6.15.

Regards,
Anup

> ---
>  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
>