linux-kernel - Re: [PATCH 06/21] KVM: TDX: Add accessors VMX VMCS helpers

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Message-ID: <92b86a71-3bbb-40a7-ae45-ab32215cce90@redhat.com>
Date: Tue, 10 Sep 2024 12:48:44 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>,
 "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
 "seanjc@...gle.com" <seanjc@...gle.com>
Cc: "Zhao, Yan Y" <yan.y.zhao@...el.com>,
 "nik.borisov@...e.com" <nik.borisov@...e.com>,
 "dmatlack@...gle.com" <dmatlack@...gle.com>, "Huang, Kai"
 <kai.huang@...el.com>, "isaku.yamahata@...il.com"
 <isaku.yamahata@...il.com>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 06/21] KVM: TDX: Add accessors VMX VMCS helpers

On 9/9/24 23:29, Edgecombe, Rick P wrote:
>> Maybe a bit large when inlined?  Maybe
>>
>>          if (unlikely(err))
>>                  tdh_vp_wr_failed(tdx, field, bit, err);
>>
>> and add tdh_vp_wr_failed to tdx.c.
> There is a tiny bit of difference between the messages:
> pr_err("TDH_VP_WR["#uclass".0x%x] = 0x%llx failed: 0x%llx\n", ...
> pr_err("TDH_VP_WR["#uclass".0x%x] |= 0x%llx failed: 0x%llx\n", ...
> pr_err("TDH_VP_WR["#uclass".0x%x] &= ~0x%llx failed: 0x%llx\n", ...
> 
> We can parameterize that part of the message, but it gets a bit tortured. Or
> just lose that bit of detail. We can take a look. Thanks.

Yes, you can:

1) have three different functions for the failure

2) leave out the value part

3) pass the mask as well to tdh_vp_wr_failed() and use it to deduce the 
=/|=/&= part, like

	if (!~mask)
		op = "=";
	else if (!value)
		op = "&= ~", value = mask;
	else if (value == mask)
		op = "|=";
	else
		op = "??, value = ";

Paolo