Received-SPF: pass (google.com: domain of linux-kernel+bounces-130197-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Date: Wed, 3 Apr 2024 09:30:11 -0700
From: Isaku Yamahata <isaku.yamahata@intel.com>
To: Sean Christopherson <seanjc@google.com>
Cc: isaku.yamahata@intel.com, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org, isaku.yamahata@gmail.com,
	Paolo Bonzini <pbonzini@redhat.com>, erdemaktas@google.com,
	Sagi Shahar <sagis@google.com>, Kai Huang <kai.huang@intel.com>,
	chen.bo@intel.com, hang.yuan@intel.com, tina.zhang@intel.com,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Xiaoyao Li <xiaoyao.li@intel.com>, isaku.yamahata@linux.intel.com
Subject: Re: [PATCH v19 027/130] KVM: TDX: Define TDX architectural
 definitions
Message-ID: <20240403163011.GD2444378@ls.amr.corp.intel.com>
References: <cover.1708933498.git.isaku.yamahata@intel.com>
 <522cbfe6e5a351f88480790fe3c3be36c82ca4b1.1708933498.git.isaku.yamahata@intel.com>
 <Zg1v4wSgPWiY1Tok@google.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <Zg1v4wSgPWiY1Tok@google.com>

On Wed, Apr 03, 2024 at 08:04:03AM -0700,
Sean Christopherson <seanjc@google.com> wrote:

> On Mon, Feb 26, 2024, isaku.yamahata@intel.com wrote:
> > +union tdx_vcpu_state_details {
> > +	struct {
> > +		u64 vmxip	: 1;
> > +		u64 reserved	: 63;
> > +	};
> > +	u64 full;
> > +};
> 
> No unions please.  KVM uses unions in a few places where they are the lesser of
> all evils, but in general, unions are frowned upon.  Bitfields in particular are
> strongly discourage, as they are a nightmare to read/review and tend to generate
> bad code.
> 
> E.g. for this one, something like (names aren't great)
> 
> static inline bool tdx_has_pending_virtual_interrupt(struct kvm_vcpu *vcpu)
> {
> 	return <get "non arch field"> & TDX_VCPU_STATE_VMXIP;
> }


Sure, let me replace them with mask and shift.
-- 
Isaku Yamahata <isaku.yamahata@intel.com>