Commit 7682a4c6 authored by Dean Nelson's avatar Dean Nelson Committed by Tony Luck
Browse files

[IA64-SGI] Silent data corruption caused by XPC V2. 



Jack Steiner identified a problem where XPC can cause a silent
data corruption.  On module load, the placement may cause the
xpc_remote_copy_buffer to span two physical pages.  DMA transfers are
done to the start virtual address translated to physical.

This patch changes the buffer from a statically allocated buffer to a
kmalloc'd buffer.  Dean Nelson reviewed this before posting.  I have
tested it in the configuration that was showing the memory corruption
and verified it works.  I also added a BUG_ON statement to help catch
this if a similar situation is encountered.

Signed-off-by: default avatarRobin Holt <holt@sgi.com>
Signed-off-by: default avatarDean Nelson <dcn@sgi.com>
Signed-off-by: default avatarJack Steiner <steiner@sgi.com>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 9f737633

arch/ia64/sn/kernel/xpc_channel.c

+2 −2
Original line number Diff line number Diff line
@@ -279,8 +279,8 @@ xpc_pull_remote_cachelines(struct xpc_partition *part, void *dst, 
		return part->reason;

	}



	bte_ret = xp_bte_copy((u64) src, (u64) ia64_tpa((u64) dst),

				(u64) cnt, (BTE_NORMAL | BTE_WACQUIRE), NULL);

	bte_ret = xp_bte_copy((u64) src, (u64) dst, (u64) cnt,

					(BTE_NORMAL | BTE_WACQUIRE), NULL);

	if (bte_ret == BTE_SUCCESS) {

		return xpcSuccess;

	}

arch/ia64/sn/kernel/xpc_main.c

+16 −12
Original line number Diff line number Diff line
@@ -1052,6 +1052,8 @@ xpc_do_exit(enum xpc_retval reason) 
	if (xpc_sysctl) {

		unregister_sysctl_table(xpc_sysctl);

	}



	kfree(xpc_remote_copy_buffer_base);

}
@@ -1212,24 +1214,20 @@ xpc_init(void) 
	partid_t partid;

	struct xpc_partition *part;

	pid_t pid;

	size_t buf_size;





	if (!ia64_platform_is("sn2")) {

		return -ENODEV;

	}



	/*

	 * xpc_remote_copy_buffer is used as a temporary buffer for bte_copy'ng

	 * various portions of a partition's reserved page. Its size is based

	 * on the size of the reserved page header and part_nasids mask. So we

	 * need to ensure that the other items will fit as well.

	 */

	if (XPC_RP_VARS_SIZE > XPC_RP_HEADER_SIZE + XP_NASID_MASK_BYTES) {

		dev_err(xpc_part, "xpc_remote_copy_buffer is not big enough\n");

		return -EPERM;

	}

	DBUG_ON((u64) xpc_remote_copy_buffer !=

				L1_CACHE_ALIGN((u64) xpc_remote_copy_buffer));



	buf_size = max(XPC_RP_VARS_SIZE,

				XPC_RP_HEADER_SIZE + XP_NASID_MASK_BYTES);

	xpc_remote_copy_buffer = xpc_kmalloc_cacheline_aligned(buf_size,

				     GFP_KERNEL, &xpc_remote_copy_buffer_base);

	if (xpc_remote_copy_buffer == NULL)

		return -ENOMEM;



	snprintf(xpc_part->bus_id, BUS_ID_SIZE, "part");

	snprintf(xpc_chan->bus_id, BUS_ID_SIZE, "chan");
@@ -1293,6 +1291,8 @@ xpc_init(void) 
		if (xpc_sysctl) {

			unregister_sysctl_table(xpc_sysctl);

		}



		kfree(xpc_remote_copy_buffer_base);

		return -EBUSY;

	}
@@ -1311,6 +1311,8 @@ xpc_init(void) 
		if (xpc_sysctl) {

			unregister_sysctl_table(xpc_sysctl);

		}



		kfree(xpc_remote_copy_buffer_base);

		return -EBUSY;

	}
@@ -1362,6 +1364,8 @@ xpc_init(void) 
		if (xpc_sysctl) {

			unregister_sysctl_table(xpc_sysctl);

		}



		kfree(xpc_remote_copy_buffer_base);

		return -EBUSY;

	}

arch/ia64/sn/kernel/xpc_partition.c

+8 −16
Original line number Diff line number Diff line
@@ -71,19 +71,15 @@ struct xpc_partition xpc_partitions[XP_MAX_PARTITIONS + 1]; 
 * Generic buffer used to store a local copy of portions of a remote

 * partition's reserved page (either its header and part_nasids mask,

 * or its vars).

 *

 * xpc_discovery runs only once and is a seperate thread that is

 * very likely going to be processing in parallel with receiving

 * interrupts.

 */

char ____cacheline_aligned xpc_remote_copy_buffer[XPC_RP_HEADER_SIZE +

							XP_NASID_MASK_BYTES];

char *xpc_remote_copy_buffer;

void *xpc_remote_copy_buffer_base;





/*

 * Guarantee that the kmalloc'd memory is cacheline aligned.

 */

static void *

void *

xpc_kmalloc_cacheline_aligned(size_t size, gfp_t flags, void **base)

{

	/* see if kmalloc will give us cachline aligned memory by default */
@@ -148,7 +144,7 @@ xpc_get_rsvd_page_pa(int nasid) 
			}

		}



		bte_res = xp_bte_copy(rp_pa, ia64_tpa(buf), buf_len,

		bte_res = xp_bte_copy(rp_pa, buf, buf_len,

					(BTE_NOTIFY | BTE_WACQUIRE), NULL);

		if (bte_res != BTE_SUCCESS) {

			dev_dbg(xpc_part, "xp_bte_copy failed %i\n", bte_res);
@@ -447,7 +443,7 @@ xpc_check_remote_hb(void) 


		/* pull the remote_hb cache line */

		bres = xp_bte_copy(part->remote_vars_pa,

					ia64_tpa((u64) remote_vars),

					(u64) remote_vars,

					XPC_RP_VARS_SIZE,

					(BTE_NOTIFY | BTE_WACQUIRE), NULL);

		if (bres != BTE_SUCCESS) {
@@ -498,8 +494,7 @@ xpc_get_remote_rp(int nasid, u64 *discovered_nasids, 




	/* pull over the reserved page header and part_nasids mask */



	bres = xp_bte_copy(*remote_rp_pa, ia64_tpa((u64) remote_rp),

	bres = xp_bte_copy(*remote_rp_pa, (u64) remote_rp,

				XPC_RP_HEADER_SIZE + xp_nasid_mask_bytes,

				(BTE_NOTIFY | BTE_WACQUIRE), NULL);

	if (bres != BTE_SUCCESS) {
@@ -554,11 +549,8 @@ xpc_get_remote_vars(u64 remote_vars_pa, struct xpc_vars *remote_vars) 
		return xpcVarsNotSet;

	}





	/* pull over the cross partition variables */



	bres = xp_bte_copy(remote_vars_pa, ia64_tpa((u64) remote_vars),

				XPC_RP_VARS_SIZE,

	bres = xp_bte_copy(remote_vars_pa, (u64) remote_vars, XPC_RP_VARS_SIZE,

				(BTE_NOTIFY | BTE_WACQUIRE), NULL);

	if (bres != BTE_SUCCESS) {

		return xpc_map_bte_errors(bres);
@@ -1239,7 +1231,7 @@ xpc_initiate_partid_to_nasids(partid_t partid, void *nasid_mask) 


	part_nasid_pa = (u64) XPC_RP_PART_NASIDS(part->remote_rp_pa);



	bte_res = xp_bte_copy(part_nasid_pa, ia64_tpa((u64) nasid_mask),

	bte_res = xp_bte_copy(part_nasid_pa, (u64) nasid_mask,

			xp_nasid_mask_bytes, (BTE_NOTIFY | BTE_WACQUIRE), NULL);



	return xpc_map_bte_errors(bte_res);

include/asm-ia64/sn/xp.h

+18 −4
Original line number Diff line number Diff line
@@ -60,23 +60,37 @@ 
 * the bte_copy() once in the hope that the failure was due to a temporary

 * aberration (i.e., the link going down temporarily).

 *

 * See bte_copy for definition of the input parameters.

 * 	src - physical address of the source of the transfer.

 *	vdst - virtual address of the destination of the transfer.

 *	len - number of bytes to transfer from source to destination.

 *	mode - see bte_copy() for definition.

 *	notification - see bte_copy() for definition.

 *

 * Note: xp_bte_copy() should never be called while holding a spinlock.

 */

static inline bte_result_t

xp_bte_copy(u64 src, u64 dest, u64 len, u64 mode, void *notification)

xp_bte_copy(u64 src, u64 vdst, u64 len, u64 mode, void *notification)

{

	bte_result_t ret;

	u64 pdst = ia64_tpa(vdst);





	ret = bte_copy(src, dest, len, mode, notification);

	/*

	 * Ensure that the physically mapped memory is contiguous.

	 *

	 * We do this by ensuring that the memory is from region 7 only.

	 * If the need should arise to use memory from one of the other

	 * regions, then modify the BUG_ON() statement to ensure that the

	 * memory from that region is always physically contiguous.

	 */

	BUG_ON(REGION_NUMBER(vdst) != RGN_KERNEL);



	ret = bte_copy(src, pdst, len, mode, notification);

	if (ret != BTE_SUCCESS) {

		if (!in_interrupt()) {

			cond_resched();

		}

		ret = bte_copy(src, dest, len, mode, notification);

		ret = bte_copy(src, pdst, len, mode, notification);

	}



	return ret;

include/asm-ia64/sn/xpc.h

+3 −1
Original line number Diff line number Diff line
@@ -683,7 +683,9 @@ extern struct xpc_vars *xpc_vars; 
extern struct xpc_rsvd_page *xpc_rsvd_page;

extern struct xpc_vars_part *xpc_vars_part;

extern struct xpc_partition xpc_partitions[XP_MAX_PARTITIONS + 1];

extern char xpc_remote_copy_buffer[];

extern char *xpc_remote_copy_buffer;

extern void *xpc_remote_copy_buffer_base;

extern void *xpc_kmalloc_cacheline_aligned(size_t, gfp_t, void **);

extern struct xpc_rsvd_page *xpc_rsvd_page_init(void);

extern void xpc_allow_IPI_ops(void);

extern void xpc_restrict_IPI_ops(void);

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