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Commit 0e4c12b4 authored by Tom Lendacky's avatar Tom Lendacky Committed by Thomas Gleixner
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x86/mm, resource: Use PAGE_KERNEL protection for ioremap of memory pages 



In order for memory pages to be properly mapped when SEV is active, it's
necessary to use the PAGE_KERNEL protection attribute as the base
protection.  This ensures that memory mapping of, e.g. ACPI tables,
receives the proper mapping attributes.

Signed-off-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: default avatarBrijesh Singh <brijesh.singh@amd.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
Tested-by: default avatarBorislav Petkov <bp@suse.de>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: kvm@vger.kernel.org
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Link: https://lkml.kernel.org/r/20171020143059.3291-11-brijesh.singh@amd.com
parent 1d2e733b

arch/x86/mm/ioremap.c

+67 −12
Original line number Diff line number Diff line
@@ -27,6 +27,11 @@ 


#include "physaddr.h"



struct ioremap_mem_flags {

	bool system_ram;

	bool desc_other;

};



/*

 * Fix up the linear direct mapping of the kernel to avoid cache attribute

 * conflicts.
@@ -56,17 +61,59 @@ int ioremap_change_attr(unsigned long vaddr, unsigned long size, 
	return err;

}



static int __ioremap_check_ram(unsigned long start_pfn, unsigned long nr_pages,

			       void *arg)

static bool __ioremap_check_ram(struct resource *res)

{

	unsigned long start_pfn, stop_pfn;

	unsigned long i;



	for (i = 0; i < nr_pages; ++i)

	if ((res->flags & IORESOURCE_SYSTEM_RAM) != IORESOURCE_SYSTEM_RAM)

		return false;



	start_pfn = (res->start + PAGE_SIZE - 1) >> PAGE_SHIFT;

	stop_pfn = (res->end + 1) >> PAGE_SHIFT;

	if (stop_pfn > start_pfn) {

		for (i = 0; i < (stop_pfn - start_pfn); ++i)

			if (pfn_valid(start_pfn + i) &&

			    !PageReserved(pfn_to_page(start_pfn + i)))

			return 1;

				return true;

	}



	return 0;

	return false;

}



static int __ioremap_check_desc_other(struct resource *res)

{

	return (res->desc != IORES_DESC_NONE);

}



static int __ioremap_res_check(struct resource *res, void *arg)

{

	struct ioremap_mem_flags *flags = arg;



	if (!flags->system_ram)

		flags->system_ram = __ioremap_check_ram(res);



	if (!flags->desc_other)

		flags->desc_other = __ioremap_check_desc_other(res);



	return flags->system_ram && flags->desc_other;

}



/*

 * To avoid multiple resource walks, this function walks resources marked as

 * IORESOURCE_MEM and IORESOURCE_BUSY and looking for system RAM and/or a

 * resource described not as IORES_DESC_NONE (e.g. IORES_DESC_ACPI_TABLES).

 */

static void __ioremap_check_mem(resource_size_t addr, unsigned long size,

				struct ioremap_mem_flags *flags)

{

	u64 start, end;



	start = (u64)addr;

	end = start + size - 1;

	memset(flags, 0, sizeof(*flags));



	walk_mem_res(start, end, flags, __ioremap_res_check);

}



/*
@@ -87,9 +134,10 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr, 
		unsigned long size, enum page_cache_mode pcm, void *caller)

{

	unsigned long offset, vaddr;

	resource_size_t pfn, last_pfn, last_addr;

	resource_size_t last_addr;

	const resource_size_t unaligned_phys_addr = phys_addr;

	const unsigned long unaligned_size = size;

	struct ioremap_mem_flags mem_flags;

	struct vm_struct *area;

	enum page_cache_mode new_pcm;

	pgprot_t prot;
@@ -108,13 +156,12 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr, 
		return NULL;

	}



	__ioremap_check_mem(phys_addr, size, &mem_flags);



	/*

	 * Don't allow anybody to remap normal RAM that we're using..

	 */

	pfn      = phys_addr >> PAGE_SHIFT;

	last_pfn = last_addr >> PAGE_SHIFT;

	if (walk_system_ram_range(pfn, last_pfn - pfn + 1, NULL,

					  __ioremap_check_ram) == 1) {

	if (mem_flags.system_ram) {

		WARN_ONCE(1, "ioremap on RAM at %pa - %pa\n",

			  &phys_addr, &last_addr);

		return NULL;
@@ -146,7 +193,15 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr, 
		pcm = new_pcm;

	}



	/*

	 * If the page being mapped is in memory and SEV is active then

	 * make sure the memory encryption attribute is enabled in the

	 * resulting mapping.

	 */

	prot = PAGE_KERNEL_IO;

	if (sev_active() && mem_flags.desc_other)

		prot = pgprot_encrypted(prot);



	switch (pcm) {

	case _PAGE_CACHE_MODE_UC:

	default:

include/linux/ioport.h

+3 −0
Original line number Diff line number Diff line
@@ -271,6 +271,9 @@ extern int 
walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,

		void *arg, int (*func)(unsigned long, unsigned long, void *));

extern int

walk_mem_res(u64 start, u64 end, void *arg,

	     int (*func)(struct resource *, void *));

extern int

walk_system_ram_res(u64 start, u64 end, void *arg,

		    int (*func)(struct resource *, void *));

extern int

kernel/resource.c

+19 −0
Original line number Diff line number Diff line
@@ -397,6 +397,8 @@ static int find_next_iomem_res(struct resource *res, unsigned long desc, 
		res->start = p->start;

	if (res->end > p->end)

		res->end = p->end;

	res->flags = p->flags;

	res->desc = p->desc;

	return 0;

}
@@ -467,6 +469,23 @@ int walk_system_ram_res(u64 start, u64 end, void *arg, 
				     arg, func);

}



/*

 * This function calls the @func callback against all memory ranges, which

 * are ranges marked as IORESOURCE_MEM and IORESOUCE_BUSY.

 */

int walk_mem_res(u64 start, u64 end, void *arg,

		 int (*func)(struct resource *, void *))

{

	struct resource res;



	res.start = start;

	res.end = end;

	res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;



	return __walk_iomem_res_desc(&res, IORES_DESC_NONE, true,

				     arg, func);

}



#if !defined(CONFIG_ARCH_HAS_WALK_MEMORY)



/*