linux-kernel - Re: [PATCH Part1 RFC v4 09/36] x86/compressed: Add helper for validating pages in the decompression stage

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Date:   Fri, 13 Aug 2021 09:21:14 -0500
From:   Brijesh Singh <brijesh.singh@....com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     brijesh.singh@....com, x86@...nel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-efi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        linux-crypto@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        "H. Peter Anvin" <hpa@...or.com>, Ard Biesheuvel <ardb@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Sergio Lopez <slp@...hat.com>, Peter Gonda <pgonda@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Dov Murik <dovmurik@...ux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@....com>,
        Michael Roth <michael.roth@....com>,
        Vlastimil Babka <vbabka@...e.cz>, tony.luck@...el.com,
        brijesh.ksingh@...il.com
Subject: Re: [PATCH Part1 RFC v4 09/36] x86/compressed: Add helper for
 validating pages in the decompression stage



On 8/13/21 5:22 AM, Borislav Petkov wrote:
>> +static void __page_state_change(unsigned long paddr, int op)
> 
> That op should be:
> 
> enum psc_op {
> 	SNP_PAGE_STATE_SHARED,
> 	SNP_PAGE_STATE_PRIVATE,
> };
> 

Noted.

> and have
> 
> static void __page_state_change(unsigned long paddr, enum psc_op op)
> 
> so that the compiler can check you're at least passing from the correct
> set of defines.
> 
>> diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
>> index ea508835ab33..aee07d1bb138 100644
>> --- a/arch/x86/include/asm/sev-common.h
>> +++ b/arch/x86/include/asm/sev-common.h
>> @@ -45,6 +45,23 @@
>>   		(((unsigned long)reg & GHCB_MSR_CPUID_REG_MASK) << GHCB_MSR_CPUID_REG_POS) | \
>>   		(((unsigned long)fn) << GHCB_MSR_CPUID_FUNC_POS))
>>   
>> +/* SNP Page State Change */
>> +#define GHCB_MSR_PSC_REQ		0x014
>> +#define SNP_PAGE_STATE_PRIVATE		1
>> +#define SNP_PAGE_STATE_SHARED		2
>> +#define GHCB_MSR_PSC_GFN_POS		12
>> +#define GHCB_MSR_PSC_GFN_MASK		GENMASK_ULL(39, 0)
>> +#define GHCB_MSR_PSC_OP_POS		52
>> +#define GHCB_MSR_PSC_OP_MASK		0xf
>> +#define GHCB_MSR_PSC_REQ_GFN(gfn, op)	\
>> +	(((unsigned long)((op) & GHCB_MSR_PSC_OP_MASK) << GHCB_MSR_PSC_OP_POS) | \
>> +	((unsigned long)((gfn) & GHCB_MSR_PSC_GFN_MASK) << GHCB_MSR_PSC_GFN_POS) | \
>> +	GHCB_MSR_PSC_REQ)
>> +
>> +#define GHCB_MSR_PSC_RESP		0x015
>> +#define GHCB_MSR_PSC_ERROR_POS		32
>> +#define GHCB_MSR_PSC_RESP_VAL(val)	((val) >> GHCB_MSR_PSC_ERROR_POS)
>> +
> 
> Also get rid of eccessive defines...

I am getting conflicting review comments on function naming, comment 
style, macro etc. While addressing the feedback I try to incorporate all 
those comments, lets see how I do in next rev.

thanks