linux-kernel - Re: [PATCH 1/4 V3] Add a function(ioremap_encrypted) for kdump when AMD sme enabled

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Date:   Wed, 20 Jun 2018 11:00:52 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Lianbo Jiang <lijiang@...hat.com>, linux-kernel@...r.kernel.org
Cc:     iommu@...ts.linux-foundation.org, kexec@...ts.infradead.org,
        dyoung@...hat.com
Subject: Re: [PATCH 1/4 V3] Add a function(ioremap_encrypted) for kdump when
 AMD sme enabled

On 6/16/2018 3:27 AM, Lianbo Jiang wrote:
> It is convenient to remap the old memory encrypted to the second
> kernel by calling ioremap_encrypted().
> 
> Signed-off-by: Lianbo Jiang <lijiang@...hat.com>
> ---
> Some changes:
> 1. remove the sme_active() check in __ioremap_caller().
> 2. put some logic into the early_memremap_pgprot_adjust() for
> early memremap.
> 
>  arch/x86/include/asm/io.h |  3 +++
>  arch/x86/mm/ioremap.c     | 28 ++++++++++++++++++++--------
>  2 files changed, 23 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
> index f6e5b93..989d60b 100644
> --- a/arch/x86/include/asm/io.h
> +++ b/arch/x86/include/asm/io.h
> @@ -192,6 +192,9 @@ extern void __iomem *ioremap_cache(resource_size_t offset, unsigned long size);
>  #define ioremap_cache ioremap_cache
>  extern void __iomem *ioremap_prot(resource_size_t offset, unsigned long size, unsigned long prot_val);
>  #define ioremap_prot ioremap_prot
> +extern void __iomem *ioremap_encrypted(resource_size_t phys_addr,
> +					unsigned long size);
> +#define ioremap_encrypted ioremap_encrypted
>  
>  /**
>   * ioremap     -   map bus memory into CPU space
> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
> index c63a545..e365fc4 100644
> --- a/arch/x86/mm/ioremap.c
> +++ b/arch/x86/mm/ioremap.c
> @@ -24,6 +24,7 @@
>  #include <asm/pgalloc.h>
>  #include <asm/pat.h>
>  #include <asm/setup.h>
> +#include <linux/crash_dump.h>
>  
>  #include "physaddr.h"
>  
> @@ -131,7 +132,8 @@ static void __ioremap_check_mem(resource_size_t addr, unsigned long size,
>   * caller shouldn't need to know that small detail.
>   */
>  static void __iomem *__ioremap_caller(resource_size_t phys_addr,
> -		unsigned long size, enum page_cache_mode pcm, void *caller)
> +		unsigned long size, enum page_cache_mode pcm,
> +		void *caller, bool encrypted)
>  {
>  	unsigned long offset, vaddr;
>  	resource_size_t last_addr;
> @@ -199,7 +201,7 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
>  	 * resulting mapping.
>  	 */
>  	prot = PAGE_KERNEL_IO;
> -	if (sev_active() && mem_flags.desc_other)
> +	if ((sev_active() && mem_flags.desc_other) || encrypted)
>  		prot = pgprot_encrypted(prot);
>  
>  	switch (pcm) {
> @@ -291,7 +293,7 @@ void __iomem *ioremap_nocache(resource_size_t phys_addr, unsigned long size)
>  	enum page_cache_mode pcm = _PAGE_CACHE_MODE_UC_MINUS;
>  
>  	return __ioremap_caller(phys_addr, size, pcm,
> -				__builtin_return_address(0));
> +				__builtin_return_address(0), false);
>  }
>  EXPORT_SYMBOL(ioremap_nocache);
>  
> @@ -324,7 +326,7 @@ void __iomem *ioremap_uc(resource_size_t phys_addr, unsigned long size)
>  	enum page_cache_mode pcm = _PAGE_CACHE_MODE_UC;
>  
>  	return __ioremap_caller(phys_addr, size, pcm,
> -				__builtin_return_address(0));
> +				__builtin_return_address(0), false);
>  }
>  EXPORT_SYMBOL_GPL(ioremap_uc);
>  
> @@ -341,7 +343,7 @@ EXPORT_SYMBOL_GPL(ioremap_uc);
>  void __iomem *ioremap_wc(resource_size_t phys_addr, unsigned long size)
>  {
>  	return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WC,
> -					__builtin_return_address(0));
> +					__builtin_return_address(0), false);
>  }
>  EXPORT_SYMBOL(ioremap_wc);
>  
> @@ -358,14 +360,21 @@ EXPORT_SYMBOL(ioremap_wc);
>  void __iomem *ioremap_wt(resource_size_t phys_addr, unsigned long size)
>  {
>  	return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WT,
> -					__builtin_return_address(0));
> +					__builtin_return_address(0), false);
>  }
>  EXPORT_SYMBOL(ioremap_wt);
>  
> +void __iomem *ioremap_encrypted(resource_size_t phys_addr, unsigned long size)
> +{
> +	return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WB,
> +				__builtin_return_address(0), true);
> +}
> +EXPORT_SYMBOL(ioremap_encrypted);
> +
>  void __iomem *ioremap_cache(resource_size_t phys_addr, unsigned long size)
>  {
>  	return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WB,
> -				__builtin_return_address(0));
> +				__builtin_return_address(0), false);
>  }
>  EXPORT_SYMBOL(ioremap_cache);
>  
> @@ -374,7 +383,7 @@ void __iomem *ioremap_prot(resource_size_t phys_addr, unsigned long size,
>  {
>  	return __ioremap_caller(phys_addr, size,
>  				pgprot2cachemode(__pgprot(prot_val)),
> -				__builtin_return_address(0));
> +				__builtin_return_address(0), false);
>  }
>  EXPORT_SYMBOL(ioremap_prot);
>  
> @@ -688,6 +697,9 @@ pgprot_t __init early_memremap_pgprot_adjust(resource_size_t phys_addr,
>  	if (encrypted_prot && memremap_should_map_decrypted(phys_addr, size))
>  		encrypted_prot = false;
>  
> +	if (sme_active() && is_kdump_kernel())
> +		encrypted_prot = false;
> +

This change doesn't seem to go with the patch description.  Maybe it
should be a separate patch?  Or provide more detail in the description
for this change.

What is this change addressing?  What early_memremap() calls were failing
that required this?  If this truly is required, you can probably move it
up into the "if (sme_active())" block a few lines higher in the function.

Thanks,
Tom

>  	return encrypted_prot ? pgprot_encrypted(prot)
>  			      : pgprot_decrypted(prot);
>  }
>