[Xen-ia64-devel] [patch 06/16] Kexec: Define macros for EFI RID

[Simon Horman <horms@xxxxxxxxxxxx>]

Macros to be called by PAL, SAL and EFI to switch into
and out of EFI RID.

Cc: Tristan Gingold <tgingold@xxxxxxx>
Cc: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
Cc: Alex Williamson <alex.williamson@xxxxxx>
Cc: Aron Griffis <aron@xxxxxx>
Signed-off-by: Simon Horman <horms@xxxxxxxxxxxx>

--- 

Thu, 22 Nov 2007 00:20:54 -0700
* Add XEN_EFI_RR_DECLARE to help consistent declarations
* Fix up vairous compile errors in the !XEN case
* Pass unsigned long as the second argement to to ia64_rid
  to ensure that it is wide enough

Mon, 03 Dec 2007 17:29:04 +0900
* Shift VRN 61 bits to the left when calling ia64_get_rr() and
  ia64_set_rr()


Thu, 24 Jan 2008 12:15:55 +0900
* Use set_one_rr_efi() instead of set_rr() so
  that TR (TLB) entries are repined as neccessary.
* Do not enable VHPT in EFI RID.
  - There seems to be no good reason to enable it,
    and the current code dies if it is enabled.
    Perhaps the VHPT TR would need to be repined?

Index: xen-unstable.hg/xen/include/asm-ia64/linux-xen/linux/efi.h
===================================================================
--- xen-unstable.hg.orig/xen/include/asm-ia64/linux-xen/linux/efi.h     
2008-02-05 16:18:41.000000000 +0900
+++ xen-unstable.hg/xen/include/asm-ia64/linux-xen/linux/efi.h  2008-02-05 
16:18:52.000000000 +0900
@@ -1,6 +1,8 @@
 #ifndef _LINUX_EFI_H
 #define _LINUX_EFI_H
 
+#ifndef __ASSEMBLY__
+
 /*
  * Extensible Firmware Interface
  * Based on 'Extensible Firmware Interface Specification' version 0.9, April 
30, 1999
@@ -419,4 +421,104 @@ struct efi_generic_dev_path {
        u16 length;
 } __attribute ((packed));
 
+#ifdef XEN
+/*
+ * According to xen/arch/ia64/xen/regionreg.c the RID space is broken
+ * up into chunks, one per domain, and 0th block is for Xen. The 0th block
+ * is broken up into small blocks, which are used for metaphisical mappins,
+ * except for the 0th small block which is used by Xen.
+ *
+ * By default each large block is 18 bits wide, which is also the minimum
+ * width. Each small block is by default 1/64 the width of a large block,
+ * which is also the maximum devision. In other words each small block is
+ * at least 12 bits wide.
+ *
+ * What isn't obvious to me is how the 0th small block is divided up.
+ * While xen/arch/ia64/xen/regionreg.c seems to handle allocating RIDs for
+ * domains, they hypervisor's RIDs seem to be handled in a bit more of an
+ * ad-hoc fashion.
+ *
+ * In xen/include/asm-ia64/mmu_context.h there is IA64_REGION_ID_KERNEL.
+ * This is used to form an RID in the follwing way:
+ *
+ * a: bit 0:     VHPT
+ * b: bit 1:     reserved (0)
+ * c: bits 2-7:  log 2 page_size
+ * d: bits 8-10: Region   (0-7, corresponding to the 8 region registers)
+ * e: bits 10-N: IA64_REGION_ID_KERNEL (0)
+ * f: bits N-53: reserved (0)
+ *
+ * N is defined by the platform. Areas c and d above form the RID, it just
+ * happens to be further divided in two due to the way that its value is
+ * calculated buy the code. This subdivision does not reflect any hardware
+ * limitation. The hardware sets the limit of the with of this area to
+ * between 18 and 24 bits.
+ *
+ * As we are only using the first 4 bits (3 bits in area d and 1 bit in
+ * area e) of RID space it easily fits inside the 0th small block, which
+ * is 12 bits wide.
+ *
+ * For EFI we use the following RID
+ *
+ * a: bit 0:     VHPT (1)
+ * b: bit 1:     reserved (0)
+ * c: bits 2-7:  log 2 page_size
+ * d: bits 8-10: Region   (0-7, corresponding to the 8 region registers) +
+ * e: bits 10-N: IA64_REGION_ID_KERNEL (1)
+ * f: bits N-53: reserved (0)
+ *
+ * + Only 0 is used as we only need one RID. Its not really important
+ *   what this number is, so long as its between 0 and 7.
+ *
+ * The nice thing about this is that we are still only using 4 bits of RID
+ * space, so it shouldn't have any chance of running into an adjacent
+ * small-block.
+ *
+ * It would actually be possible to just use a IA64_REGION_ID_KERNEL
+ * based RID for EFI use. The important thing is that it is in the 0th
+ * small block, and that not available to domains. But as we have
+ * lots of space, its seems to be nice and clean to just use a separate
+ * RID for EFI.
+ *
+ * This can be trivially changed by updating the definition of XEN_EFI_RID.
+ */
+
+#define XEN_EFI_RR_SAVE(rr6, rr7) do {                 \
+       rr6 = ia64_get_rr(6UL << 61);                   \
+       rr7 = ia64_get_rr(7UL << 61);                   \
+       set_one_rr_efi(6UL << 61, XEN_EFI_RID);         \
+       set_one_rr_efi(7UL << 61, XEN_EFI_RID);         \
+       ia64_srlz_d();                                  \
+} while (0)
+
+#define XEN_EFI_RR_RESTORE(rr6, rr7) do {              \
+       set_one_rr_efi(6UL << 61, rr6);                 \
+       set_one_rr_efi(7UL << 61, rr7);                 \
+       ia64_srlz_d();                                  \
+} while (0)
+
+#else
+/* Just use rr6 and rr7 in a dummy fashion here to get
+ * rid of compiler warnings - a better solution should
+ * be found if this code is ever actually used */
+#define XEN_EFI_RR_SAVE(rr6, rr7)       do { rr6 = 0; rr7 = 0; } while (0)
+#define XEN_EFI_RR_RESTORE(rr6, rr7)    do {} while (0)
+#endif /* XEN */
+
+#define XEN_EFI_RR_DECLARE(rr6, rr7)   unsigned long rr6, rr7;
+
+#endif /* !__ASSEMBLY__ */
+
+#ifdef XEN
+#include <asm/mmu_context.h> /* For IA64_REGION_ID_EFI and ia64_rid() */
+#include <asm/pgtable.h>     /* IA64_GRANULE_SHIFT */
+#ifdef __ASSEMBLY__
+#define XEN_EFI_RID_NO 0
+#else
+#define XEN_EFI_RID_NO 0UL
+#endif
+#define XEN_EFI_RID ((ia64_rid(XEN_IA64_REGION_ID_EFI, XEN_EFI_RID_NO) << 8) |\
+                    (IA64_GRANULE_SHIFT << 2))
+#endif /* XEN */
+
 #endif /* _LINUX_EFI_H */
Index: xen-unstable.hg/xen/include/asm-ia64/mmu_context.h
===================================================================
--- xen-unstable.hg.orig/xen/include/asm-ia64/mmu_context.h     2008-02-05 
16:18:41.000000000 +0900
+++ xen-unstable.hg/xen/include/asm-ia64/mmu_context.h  2008-02-05 
16:18:52.000000000 +0900
@@ -3,6 +3,7 @@
 //dummy file to resolve non-arch-indep include
 #ifdef XEN
 #define IA64_REGION_ID_KERNEL 0
+#define XEN_IA64_REGION_ID_EFI 1
 #define ia64_rid(ctx,addr)     (((ctx) << 3) | (addr >> 61))
 
 #ifndef __ASSEMBLY__

-- 

-- 
Horms


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