From: Marc Zyngier <maz@kernel.org>
To: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Cc: linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Andrew Scull <ascull@google.com>, Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Quentin Perret <qperret@google.com>,
David Brazdil <dbrazdil@google.com>,
kernel-team@android.com
Subject: Re: [PATCH v2 11/11] KVM: arm64: Get rid of the AArch32 register mapping code
Date: Thu, 23 May 2024 17:04:05 +0100 [thread overview]
Message-ID: <86le40ms5m.wl-maz@kernel.org> (raw)
In-Reply-To: <66a7077c5df86d0a541237996382ae583d690a14.camel@linux.ibm.com>
Hi Nina,
On Thu, 23 May 2024 15:25:21 +0100,
Nina Schoetterl-Glausch <nsg@linux.ibm.com> wrote:
>
> On Mon, 2020-11-02 at 16:40 +0000, Marc Zyngier wrote:
Wow, you're digging out the old dregs... But it is worth it!
>
> [...]
>
> > diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
> > index dfb5218137ca..3f23f7478d2a 100644
> > --- a/arch/arm64/kvm/guest.c
> > +++ b/arch/arm64/kvm/guest.c
> > @@ -252,10 +252,32 @@ static int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> > memcpy(addr, valp, KVM_REG_SIZE(reg->id));
>
> I was looking at KVM_(G|S)ET_ONE_REG implementations and something looks off to me here:
>
> ...
>
> if (off == KVM_REG_ARM_CORE_REG(regs.pstate)) {
> u64 mode = (*(u64 *)valp) & PSR_AA32_MODE_MASK;
> switch (mode) {
>
> Masking and switch over mode here...
>
> case PSR_AA32_MODE_USR:
> if (!kvm_supports_32bit_el0())
> return -EINVAL;
> break;
> case PSR_AA32_MODE_FIQ:
> case PSR_AA32_MODE_IRQ:
> ...
> >
> > if (*vcpu_cpsr(vcpu) & PSR_MODE32_BIT) {
> > - int i;
> > + int i, nr_reg;
> > +
> > + switch (*vcpu_cpsr(vcpu)) {
>
> ...but switching over mode without masking here.
> I don't know if this is as intended, but I thought I'd mention it.
Amazing. Thanks for spotting this. This is indeed broken. I guess this
was not spotted because userspace is not totally broken itself.
Do you want to submit a fix adding the masking back? or should I do it
myself?
Thanks again,
M.
--
Without deviation from the norm, progress is not possible.
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next prev parent reply other threads:[~2024-05-23 16:04 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-02 16:40 [PATCH v2 00/11] KVM: arm64: Move PC/ELR/SPSR/PSTATE updatess to EL2 Marc Zyngier
2020-11-02 16:40 ` [PATCH v2 01/11] KVM: arm64: Don't adjust PC on SError during SMC trap Marc Zyngier
2020-11-02 16:40 ` [PATCH v2 02/11] KVM: arm64: Move kvm_vcpu_trap_il_is32bit into kvm_skip_instr32() Marc Zyngier
2020-11-02 16:40 ` [PATCH v2 03/11] KVM: arm64: Make kvm_skip_instr() and co private to HYP Marc Zyngier
2021-05-05 14:23 ` Zenghui Yu
2021-05-05 16:46 ` Marc Zyngier
2021-05-06 6:33 ` Marc Zyngier
2021-05-06 11:43 ` Zenghui Yu
2021-05-06 14:29 ` Marc Zyngier
2021-05-09 13:07 ` Zenghui Yu
2021-05-10 7:59 ` Marc Zyngier
2021-05-06 17:17 ` Marc Zyngier
2020-11-02 16:40 ` [PATCH v2 04/11] KVM: arm64: Move PC rollback on SError " Marc Zyngier
2020-11-02 16:40 ` [PATCH v2 05/11] KVM: arm64: Move VHE direct sysreg accessors into kvm_host.h Marc Zyngier
2020-11-02 16:40 ` [PATCH v2 06/11] KVM: arm64: Add basic hooks for injecting exceptions from EL2 Marc Zyngier
2020-11-02 16:40 ` [PATCH v2 07/11] KVM: arm64: Inject AArch64 exceptions from HYP Marc Zyngier
2020-11-02 16:40 ` [PATCH v2 08/11] KVM: arm64: Inject AArch32 " Marc Zyngier
2020-11-02 16:40 ` [PATCH v2 09/11] KVM: arm64: Remove SPSR manipulation primitives Marc Zyngier
2020-11-02 16:40 ` [PATCH v2 10/11] KVM: arm64: Consolidate exception injection Marc Zyngier
2020-11-02 16:40 ` [PATCH v2 11/11] KVM: arm64: Get rid of the AArch32 register mapping code Marc Zyngier
2024-05-23 14:25 ` Nina Schoetterl-Glausch
2024-05-23 16:04 ` Marc Zyngier [this message]
2024-05-23 16:19 ` Nina Schoetterl-Glausch
2024-05-23 18:18 ` Marc Zyngier
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