[PATCH v3] Remove the memory encryption mask to obtain the true physical address

lijiang lijiang at redhat.com
Mon Mar 11 18:13:33 PDT 2019


在 2019年03月12日 03:43, Kazuhito Hagio 写道:
> -----Original Message-----
>>>> [PATCH v3] Remove the memory encryption mask to obtain the true physical address
>>>
>>> I forgot to comment on the subject and the commit log..
>>> I'll change this to
>>>
>>>   x86_64: Add support for AMD Secure Memory Encryption
>>>
>>> On 1/29/2019 9:48 PM, Lianbo Jiang wrote:
>>>> For AMD machine with SME feature, if SME is enabled in the first
>>>> kernel, the crashed kernel's page table(pgd/pud/pmd/pte) contains
>>>> the memory encryption mask, so makedumpfile needs to remove the
>>>> memory encryption mask to obtain the true physical address.
>>>
>>> I added a few official words from some documents:
>>> ---
>>> On AMD machine with Secure Memory Encryption (SME) feature, if SME is
>>> enabled, page tables contain a specific attribute bit (C-bit) in their
>>> entries to indicate whether a page is encrypted or unencrypted.
>>>
>>> So get NUMBER(sme_mask) from vmcoreinfo, which stores the value of
>>> the C-bit position, and drop it to obtain the true physical address.
>>> ---
>>>
>>> If these are OK, I'll modify them when merging, so you don't need
>>> to repost.
>>>
>>
>> It's fine to me. Thank you, Kazu.
>>
>> Regards,
>> Lianbo
>>
>>> And, I'm thinking to merge this after the kernel patch gets merged
>>> into the mainline.
> 
> Hi Lianbo,
> 
> I found your patch upstream. Applied to the devel branch.
> 

Thank you, Kazu.

Regards,
Lianbo

> Thank you!
> Kazu
> 
> 
>>>
>>> Thanks for your work.
>>> Kazu
>>>
>>>>
>>>> Signed-off-by: Lianbo Jiang <lijiang at redhat.com>
>>>> ---
>>>> Changes since v1:
>>>> 1. Merge them into a patch.
>>>> 2. The sme_mask is not an enum number, remove it.
>>>> 3. Sanity check whether the sme_mask is in vmcoreinfo.
>>>> 4. Deal with the huge pages case.
>>>> 5. Cover the 5-level path.
>>>>
>>>> Changes since v2:
>>>> 1. Change the sme_me_mask to entry_mask.
>>>> 2. No need to remove the mask when makedumpfile prints out the
>>>>    value of the entry.
>>>> 3. Remove the sme mask from the pte at the end of the __vtop4_x86_64().
>>>> 4. Also need to remove the sme mask from page table entry in
>>>>    find_vmemmap_x86_64()
>>>>
>>>>  arch/x86_64.c  | 30 +++++++++++++++++++-----------
>>>>  makedumpfile.c |  4 ++++
>>>>  makedumpfile.h |  1 +
>>>>  3 files changed, 24 insertions(+), 11 deletions(-)
>>>>
>>>> diff --git a/arch/x86_64.c b/arch/x86_64.c
>>>> index 537fb78..9977466 100644
>>>> --- a/arch/x86_64.c
>>>> +++ b/arch/x86_64.c
>>>> @@ -291,6 +291,7 @@ __vtop4_x86_64(unsigned long vaddr, unsigned long pagetable)
>>>>  	unsigned long page_dir, pgd, pud_paddr, pud_pte, pmd_paddr, pmd_pte;
>>>>  	unsigned long pte_paddr, pte;
>>>>  	unsigned long p4d_paddr, p4d_pte;
>>>> +	unsigned long entry_mask = ENTRY_MASK;
>>>>
>>>>  	/*
>>>>  	 * Get PGD.
>>>> @@ -302,6 +303,9 @@ __vtop4_x86_64(unsigned long vaddr, unsigned long pagetable)
>>>>  			return NOT_PADDR;
>>>>  	}
>>>>
>>>> +	if (NUMBER(sme_mask) != NOT_FOUND_NUMBER)
>>>> +		entry_mask &= ~(NUMBER(sme_mask));
>>>> +
>>>>  	if (check_5level_paging()) {
>>>>  		page_dir += pgd5_index(vaddr) * sizeof(unsigned long);
>>>>  		if (!readmem(PADDR, page_dir, &pgd, sizeof pgd)) {
>>>> @@ -318,7 +322,7 @@ __vtop4_x86_64(unsigned long vaddr, unsigned long pagetable)
>>>>  		/*
>>>>  		 * Get P4D.
>>>>  		 */
>>>> -		p4d_paddr  = pgd & ENTRY_MASK;
>>>> +		p4d_paddr  = pgd & entry_mask;
>>>>  		p4d_paddr += p4d_index(vaddr) * sizeof(unsigned long);
>>>>  		if (!readmem(PADDR, p4d_paddr, &p4d_pte, sizeof p4d_pte)) {
>>>>  			ERRMSG("Can't get p4d_pte (p4d_paddr:%lx).\n", p4d_paddr);
>>>> @@ -331,7 +335,7 @@ __vtop4_x86_64(unsigned long vaddr, unsigned long pagetable)
>>>>  			ERRMSG("Can't get a valid p4d_pte.\n");
>>>>  			return NOT_PADDR;
>>>>  		}
>>>> -		pud_paddr  = p4d_pte & ENTRY_MASK;
>>>> +		pud_paddr  = p4d_pte & entry_mask;
>>>>  	}else {
>>>>  		page_dir += pgd_index(vaddr) * sizeof(unsigned long);
>>>>  		if (!readmem(PADDR, page_dir, &pgd, sizeof pgd)) {
>>>> @@ -345,7 +349,7 @@ __vtop4_x86_64(unsigned long vaddr, unsigned long pagetable)
>>>>  			ERRMSG("Can't get a valid pgd.\n");
>>>>  			return NOT_PADDR;
>>>>  		}
>>>> -		pud_paddr  = pgd & ENTRY_MASK;
>>>> +		pud_paddr  = pgd & entry_mask;
>>>>  	}
>>>>
>>>>  	/*
>>>> @@ -364,13 +368,13 @@ __vtop4_x86_64(unsigned long vaddr, unsigned long pagetable)
>>>>  		return NOT_PADDR;
>>>>  	}
>>>>  	if (pud_pte & _PAGE_PSE)	/* 1GB pages */
>>>> -		return (pud_pte & ENTRY_MASK & PUD_MASK) +
>>>> +		return (pud_pte & entry_mask & PUD_MASK) +
>>>>  			(vaddr & ~PUD_MASK);
>>>>
>>>>  	/*
>>>>  	 * Get PMD.
>>>>  	 */
>>>> -	pmd_paddr  = pud_pte & ENTRY_MASK;
>>>> +	pmd_paddr  = pud_pte & entry_mask;
>>>>  	pmd_paddr += pmd_index(vaddr) * sizeof(unsigned long);
>>>>  	if (!readmem(PADDR, pmd_paddr, &pmd_pte, sizeof pmd_pte)) {
>>>>  		ERRMSG("Can't get pmd_pte (pmd_paddr:%lx).\n", pmd_paddr);
>>>> @@ -384,13 +388,13 @@ __vtop4_x86_64(unsigned long vaddr, unsigned long pagetable)
>>>>  		return NOT_PADDR;
>>>>  	}
>>>>  	if (pmd_pte & _PAGE_PSE)	/* 2MB pages */
>>>> -		return (pmd_pte & ENTRY_MASK & PMD_MASK) +
>>>> +		return (pmd_pte & entry_mask & PMD_MASK) +
>>>>  			(vaddr & ~PMD_MASK);
>>>>
>>>>  	/*
>>>>  	 * Get PTE.
>>>>  	 */
>>>> -	pte_paddr  = pmd_pte & ENTRY_MASK;
>>>> +	pte_paddr  = pmd_pte & entry_mask;
>>>>  	pte_paddr += pte_index(vaddr) * sizeof(unsigned long);
>>>>  	if (!readmem(PADDR, pte_paddr, &pte, sizeof pte)) {
>>>>  		ERRMSG("Can't get pte (pte_paddr:%lx).\n", pte_paddr);
>>>> @@ -403,7 +407,7 @@ __vtop4_x86_64(unsigned long vaddr, unsigned long pagetable)
>>>>  		ERRMSG("Can't get a valid pte.\n");
>>>>  		return NOT_PADDR;
>>>>  	}
>>>> -	return (pte & ENTRY_MASK) + PAGEOFFSET(vaddr);
>>>> +	return (pte & entry_mask) + PAGEOFFSET(vaddr);
>>>>  }
>>>>
>>>>  unsigned long long
>>>> @@ -636,6 +640,7 @@ find_vmemmap_x86_64()
>>>>  	unsigned long pmd, tpfn;
>>>>  	unsigned long pvaddr = 0;
>>>>  	unsigned long data_addr = 0, last_data_addr = 0, start_data_addr = 0;
>>>> +	unsigned long pmask = PMASK;
>>>>  	/*
>>>>  	 * data_addr is the paddr of the page holding the page structs.
>>>>  	 * We keep lists of contiguous pages and the pfn's that their
>>>> @@ -656,6 +661,9 @@ find_vmemmap_x86_64()
>>>>  		return FAILED;
>>>>  	}
>>>>
>>>> +	if (NUMBER(sme_mask) != NOT_FOUND_NUMBER)
>>>> +		pmask &= ~(NUMBER(sme_mask));
>>>> +
>>>>  	pagestructsize = size_table.page;
>>>>  	hugepagesize = PTRS_PER_PMD * info->page_size;
>>>>  	vaddr_base = info->vmemmap_start;
>>>> @@ -686,7 +694,7 @@ find_vmemmap_x86_64()
>>>>  		}
>>>>
>>>>  		/* mask the pgd entry for the address of the pud page */
>>>> -		pud_addr &= PMASK;
>>>> +		pud_addr &= pmask;
>>>>  		if (pud_addr == 0)
>>>>  			  continue;
>>>>  		/* read the entire pud page */
>>>> @@ -699,7 +707,7 @@ find_vmemmap_x86_64()
>>>>  		/* pudp points to an entry in the pud page */
>>>>  		for (pudp = (unsigned long *)pud_page, pudindex = 0;
>>>>  					pudindex < PTRS_PER_PUD; pudindex++, pudp++) {
>>>> -			pmd_addr = *pudp & PMASK;
>>>> +			pmd_addr = *pudp & pmask;
>>>>  			/* read the entire pmd page */
>>>>  			if (pmd_addr == 0)
>>>>  				continue;
>>>> @@ -741,7 +749,7 @@ find_vmemmap_x86_64()
>>>>  				 * - we discontiguous page is a string of valids
>>>>  				 */
>>>>  				if (pmd) {
>>>> -					data_addr = (pmd & PMASK);
>>>> +					data_addr = (pmd & pmask);
>>>>  					if (start_range) {
>>>>  						/* first-time kludge */
>>>>  						start_data_addr = data_addr;
>>>> diff --git a/makedumpfile.c b/makedumpfile.c
>>>> index 8923538..2237eb8 100644
>>>> --- a/makedumpfile.c
>>>> +++ b/makedumpfile.c
>>>> @@ -977,6 +977,8 @@ next_page:
>>>>  	read_size = MIN(info->page_size - PAGEOFFSET(paddr), size);
>>>>
>>>>  	pgaddr = PAGEBASE(paddr);
>>>> +	if (NUMBER(sme_mask) != NOT_FOUND_NUMBER)
>>>> +		pgaddr = pgaddr & ~(NUMBER(sme_mask));
>>>>  	pgbuf = cache_search(pgaddr, read_size);
>>>>  	if (!pgbuf) {
>>>>  		++cache_miss;
>>>> @@ -2276,6 +2278,7 @@ write_vmcoreinfo_data(void)
>>>>  	WRITE_NUMBER("NR_FREE_PAGES", NR_FREE_PAGES);
>>>>  	WRITE_NUMBER("N_ONLINE", N_ONLINE);
>>>>  	WRITE_NUMBER("pgtable_l5_enabled", pgtable_l5_enabled);
>>>> +	WRITE_NUMBER("sme_mask", sme_mask);
>>>>
>>>>  	WRITE_NUMBER("PG_lru", PG_lru);
>>>>  	WRITE_NUMBER("PG_private", PG_private);
>>>> @@ -2672,6 +2675,7 @@ read_vmcoreinfo(void)
>>>>  	READ_NUMBER("NR_FREE_PAGES", NR_FREE_PAGES);
>>>>  	READ_NUMBER("N_ONLINE", N_ONLINE);
>>>>  	READ_NUMBER("pgtable_l5_enabled", pgtable_l5_enabled);
>>>> +	READ_NUMBER("sme_mask", sme_mask);
>>>>
>>>>  	READ_NUMBER("PG_lru", PG_lru);
>>>>  	READ_NUMBER("PG_private", PG_private);
>>>> diff --git a/makedumpfile.h b/makedumpfile.h
>>>> index 73813ed..e97b2e7 100644
>>>> --- a/makedumpfile.h
>>>> +++ b/makedumpfile.h
>>>> @@ -1912,6 +1912,7 @@ struct number_table {
>>>>  	long	NR_FREE_PAGES;
>>>>  	long	N_ONLINE;
>>>>  	long	pgtable_l5_enabled;
>>>> +	long	sme_mask;
>>>>
>>>>  	/*
>>>>   	* Page flags
>>>> --
>>>> 2.17.1
>>>>
>>>
>>>
> 
> 



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