Commit 2efbc58f authored by Anshuman Khandual's avatar Anshuman Khandual Committed by Michael Ellerman
Browse files

powerpc/pseries/svm: Force SWIOTLB for secure guests 



SWIOTLB checks range of incoming CPU addresses to be bounced and sees if
the device can access it through its DMA window without requiring bouncing.
In such cases it just chooses to skip bouncing. But for cases like secure
guests on powerpc platform all addresses need to be bounced into the shared
pool of memory because the host cannot access it otherwise. Hence the need
to do the bouncing is not related to device's DMA window and use of bounce
buffers is forced by setting swiotlb_force.

Also, connect the shared memory conversion functions into the
ARCH_HAS_MEM_ENCRYPT hooks and call swiotlb_update_mem_attributes() to
convert SWIOTLB's memory pool to shared memory.

Signed-off-by: default avatarAnshuman Khandual <khandual@linux.vnet.ibm.com>
[ bauerman: Use ARCH_HAS_MEM_ENCRYPT hooks to share swiotlb memory pool. ]
Signed-off-by: default avatarThiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190820021326.6884-15-bauerman@linux.ibm.com
parent edea902c

arch/powerpc/include/asm/mem_encrypt.h

0 → 100644
+26 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0+ */

/*

 * SVM helper functions

 *

 * Copyright 2018 IBM Corporation

 */



#ifndef _ASM_POWERPC_MEM_ENCRYPT_H

#define _ASM_POWERPC_MEM_ENCRYPT_H



#include <asm/svm.h>



static inline bool mem_encrypt_active(void)

{

	return is_secure_guest();

}



static inline bool force_dma_unencrypted(struct device *dev)

{

	return is_secure_guest();

}



int set_memory_encrypted(unsigned long addr, int numpages);

int set_memory_decrypted(unsigned long addr, int numpages);



#endif /* _ASM_POWERPC_MEM_ENCRYPT_H */

arch/powerpc/platforms/pseries/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -149,6 +149,9 @@ config PAPR_SCM 
config PPC_SVM

	bool "Secure virtual machine (SVM) support for POWER"

	depends on PPC_PSERIES

	select SWIOTLB

	select ARCH_HAS_MEM_ENCRYPT

	select ARCH_HAS_FORCE_DMA_UNENCRYPTED

	help

	 There are certain POWER platforms which support secure guests using

	 the Protected Execution Facility, with the help of an Ultravisor

arch/powerpc/platforms/pseries/svm.c

+45 −0
Original line number Diff line number Diff line
@@ -7,8 +7,53 @@ 
 */



#include <linux/mm.h>

#include <asm/machdep.h>

#include <asm/svm.h>

#include <asm/swiotlb.h>

#include <asm/ultravisor.h>



static int __init init_svm(void)

{

	if (!is_secure_guest())

		return 0;



	/* Don't release the SWIOTLB buffer. */

	ppc_swiotlb_enable = 1;



	/*

	 * Since the guest memory is inaccessible to the host, devices always

	 * need to use the SWIOTLB buffer for DMA even if dma_capable() says

	 * otherwise.

	 */

	swiotlb_force = SWIOTLB_FORCE;



	/* Share the SWIOTLB buffer with the host. */

	swiotlb_update_mem_attributes();



	return 0;

}

machine_early_initcall(pseries, init_svm);



int set_memory_encrypted(unsigned long addr, int numpages)

{

	if (!PAGE_ALIGNED(addr))

		return -EINVAL;



	uv_unshare_page(PHYS_PFN(__pa(addr)), numpages);



	return 0;

}



int set_memory_decrypted(unsigned long addr, int numpages)

{

	if (!PAGE_ALIGNED(addr))

		return -EINVAL;



	uv_share_page(PHYS_PFN(__pa(addr)), numpages);



	return 0;

}



/* There's one dispatch log per CPU. */

#define NR_DTL_PAGE (DISPATCH_LOG_BYTES * CONFIG_NR_CPUS / PAGE_SIZE)

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