linux-kernel - Re: [PATCH 1/2 RESEND v10] x86/mm, resource: add a new I/O resource descriptor 'IORES_DESC

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Message-ID: <c94f887e-2ac8-49c6-e02c-92453e1ad894@redhat.com>
Date:   Tue, 2 Apr 2019 20:02:04 +0800
From:   lijiang <lijiang@...hat.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
        tglx@...utronix.de, mingo@...hat.com, akpm@...ux-foundation.org,
        dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org,
        x86@...nel.org, hpa@...or.com, dyoung@...hat.com, bhe@...hat.com,
        Thomas.Lendacky@....com
Subject: Re: [PATCH 1/2 RESEND v10] x86/mm, resource: add a new I/O resource
 descriptor 'IORES_DESC_RESERVED'

在 2019年04月02日 17:06, Borislav Petkov 写道:
> On Fri, Mar 29, 2019 at 08:39:13PM +0800, Lianbo Jiang wrote:
>> -static int __ioremap_check_desc_other(struct resource *res)
>> +/*
>> + * Originally, these areas described as IORES_DESC_NONE are not mapped
>> + * as encrypted when using ioremap(), for example, E820_TYPE_{RESERVED,
>> + * RESERVED_KERN,RAM,UNUSABLE}, etc. It checks for a resource that is
>> + * not described as IORES_DESC_NONE, which can make sure the reserved
>> + * areas are not mapped as encrypted when using ioremap().
>> + *
>> + * Now IORES_DESC_RESERVED has been created for the reserved areas so
>> + * the check needs to be expanded so that these areas are not mapped
>> + * encrypted when using ioremap().
>> + */
>> +static int __ioremap_check_desc_none_and_reserved(struct resource *res)
>>  {
>> -	return (res->desc != IORES_DESC_NONE);
>> +	return ((res->desc != IORES_DESC_NONE) &&
> 
> Why is this still checking IORES_DESC_NONE when the idea is to have this
> specific IORES_DESC_RESERVED for all marked as *reserved* regions in
> e820 which should not be mapped encrypted?
> 
> IOW, which regions are still marked as IORES_DESC_NONE and should not be
> mapped encrypted?
> 
Thanks for your comment.

These regions(E820_TYPE_{RESERVED_KERN,RAM,UNUSABLE}) are still marked as
IORES_DESC_NONE and should not be mapped encrypted when using ioremap().
Please refer to the following function.

static unsigned long __init e820_type_to_iores_desc(struct e820_entry *entry)
{
        switch (entry->type) {
        case E820_TYPE_ACPI:            return IORES_DESC_ACPI_TABLES;
        case E820_TYPE_NVS:             return IORES_DESC_ACPI_NV_STORAGE;
        case E820_TYPE_PMEM:            return IORES_DESC_PERSISTENT_MEMORY;
        case E820_TYPE_PRAM:            return IORES_DESC_PERSISTENT_MEMORY_LEGACY;
	case E820_TYPE_RESERVED:        return IORES_DESC_RESERVED;
        case E820_TYPE_RESERVED_KERN:   /* Fall-through: */
        case E820_TYPE_RAM:             /* Fall-through: */
        case E820_TYPE_UNUSABLE:        /* Fall-through: */
        default:                        return IORES_DESC_NONE;
        }
}


Thanks.
Lianbo