linux-kernel - Re: [PATCH v2 1/4] KVM: arm64: Trap FFA

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Message-ID: <ZmrePPCdc28OLyPb@google.com>
Date: Thu, 13 Jun 2024 11:55:40 +0000
From: Sebastian Ene <sebastianene@...gle.com>
To: Sudeep Holla <sudeep.holla@....com>
Cc: catalin.marinas@....com, james.morse@....com, jean-philippe@...aro.org,
	maz@...nel.org, oliver.upton@...ux.dev, qperret@...gle.com,
	qwandor@...gle.com, suzuki.poulose@....com, tabba@...gle.com,
	will@...nel.org, yuzenghui@...wei.com, lpieralisi@...nel.org,
	kvmarm@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, kernel-team@...roid.com
Subject: Re: [PATCH v2 1/4] KVM: arm64: Trap FFA_VERSION host call in pKVM

On Wed, Jun 12, 2024 at 02:58:31PM +0100, Sudeep Holla wrote:
> On Wed, May 15, 2024 at 05:22:55PM +0000, Sebastian Ene wrote:
> > The pKVM hypervisor initializes with FF-A version 1.0. The spec requires
> > that no other FF-A calls to be issued before the version negotiation
> > phase is complete. Split the hypervisor proxy initialization code in two
> > parts so that we can move the later one after the host negotiates its
> > version.
> 
> Blank line here would be nice.
> 

Added blank line.

> > Without trapping the call, the host drivers can negotiate a higher
> > version number with TEE which can result in a different memory layout
> > described during the memory sharing calls.
> >
> 
> LGTM(apart from minor nits),
> 
> Reviewed-by: Sudeep Holla <sudeep.holla@....com>
> 

Thanks Sudeep, I will incorporate the tag it in v3.

> > Signed-off-by: Sebastian Ene <sebastianene@...gle.com>
> > ---
> >  arch/arm64/kvm/hyp/nvhe/ffa.c | 123 +++++++++++++++++++++++++---------
> >  1 file changed, 92 insertions(+), 31 deletions(-)
> >
> > diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
> > index 320f2eaa14a9..72f1206c85fb 100644
> > --- a/arch/arm64/kvm/hyp/nvhe/ffa.c
> > +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
> > @@ -1,4 +1,5 @@
> >  // SPDX-License-Identifier: GPL-2.0-only
> > +//
> 
> It should be OK but still spurious for $subject 😉
> 
> [...]
> 

Dropped this.

> > @@ -700,7 +789,6 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id)
> >  int hyp_ffa_init(void *pages)
> >  {
> >  	struct arm_smccc_res res;
> > -	size_t min_rxtx_sz;
> >  	void *tx, *rx;
> >
> >  	if (kvm_host_psci_config.smccc_version < ARM_SMCCC_VERSION_1_2)
> > @@ -726,35 +814,7 @@ int hyp_ffa_init(void *pages)
> >  	if (FFA_MAJOR_VERSION(res.a0) != 1)
> >  		return -EOPNOTSUPP;
> >
> > -	arm_smccc_1_1_smc(FFA_ID_GET, 0, 0, 0, 0, 0, 0, 0, &res);
> > -	if (res.a0 != FFA_SUCCESS)
> > -		return -EOPNOTSUPP;
> > -
> > -	if (res.a2 != HOST_FFA_ID)
> > -		return -EINVAL;
> > -
> > -	arm_smccc_1_1_smc(FFA_FEATURES, FFA_FN64_RXTX_MAP,
> > -			  0, 0, 0, 0, 0, 0, &res);
> > -	if (res.a0 != FFA_SUCCESS)
> > -		return -EOPNOTSUPP;
> > -
> > -	switch (res.a2) {
> > -	case FFA_FEAT_RXTX_MIN_SZ_4K:
> > -		min_rxtx_sz = SZ_4K;
> > -		break;
> > -	case FFA_FEAT_RXTX_MIN_SZ_16K:
> > -		min_rxtx_sz = SZ_16K;
> > -		break;
> > -	case FFA_FEAT_RXTX_MIN_SZ_64K:
> > -		min_rxtx_sz = SZ_64K;
> > -		break;
> > -	default:
> > -		return -EINVAL;
> > -	}
> > -
> > -	if (min_rxtx_sz > PAGE_SIZE)
> > -		return -EOPNOTSUPP;
> > -
> > +	hyp_ffa_version = FFA_VERSION_1_0;
> >  	tx = pages;
> >  	pages += KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE;
> >  	rx = pages;
> > @@ -773,8 +833,9 @@ int hyp_ffa_init(void *pages)
> >  	};
> >
> >  	host_buffers = (struct kvm_ffa_buffers) {
> > -		.lock	= __HYP_SPIN_LOCK_UNLOCKED,
> > +		.lock   = __HYP_SPIN_LOCK_UNLOCKED,
> 
> Spurious or intentional whitespace change ? I can't make out from the mail.
> 
> --

I dropped this, it was a spurious whitespace change.

> Regards,
> Sudeep

Cheers,
Seb