ia64/pv_ops/xen: paravirtualize read/write ar.itc and ar.itm

paravirtualize ar.itc and ar.itm in order to support save/restore.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Tony Luck <tony.luck@intel.com>

6 files changed, 123 insertions, 2 deletions

diff --git a/arch/ia64/include/asm/xen/inst.h b/arch/ia64/include/asm/xen/inst.h
index e8e01b28d2ae..90537dc15efe 100644
--- a/arch/ia64/include/asm/xen/inst.h
+++ b/arch/ia64/include/asm/xen/inst.h
@@ -113,6 +113,27 @@
 .endm
 #define MOV_FROM_PSR(pred, reg, clob)   __MOV_FROM_PSR pred, reg, clob
 
+/* assuming ar.itc is read with interrupt disabled. */
+#define MOV_FROM_ITC(pred, pred_clob, reg, clob)                \
+(pred)  movl clob = XSI_ITC_OFFSET;                             \
+        ;;                                                      \
+(pred)  ld8 clob = [clob];                                      \
+(pred)  mov reg = ar.itc;                                       \
+        ;;                                                      \
+(pred)  add reg = reg, clob;                                    \
+        ;;                                                      \
+(pred)  movl clob = XSI_ITC_LAST;                               \
+        ;;                                                      \
+(pred)  ld8 clob = [clob];                                      \
+        ;;                                                      \
+(pred)  cmp.geu.unc pred_clob, p0 = clob, reg;                  \
+        ;;                                                      \
+(pred_clob)     add reg = 1, clob;                              \
+        ;;                                                      \
+(pred)  movl clob = XSI_ITC_LAST;                               \
+        ;;                                                      \
+(pred)  st8 [clob] = reg
+
 
 #define MOV_TO_IFA(reg, clob)   \
         movl clob = XSI_IFA;    \
diff --git a/arch/ia64/include/asm/xen/interface.h b/arch/ia64/include/asm/xen/interface.h
index f00fab40854d..e951e740bdf2 100644
--- a/arch/ia64/include/asm/xen/interface.h
+++ b/arch/ia64/include/asm/xen/interface.h
@@ -209,6 +209,15 @@ struct mapped_regs {
                         unsigned long krs[8];   /* kernel registers */
                         unsigned long tmp[16];  /* temp registers
                                                    (e.g. for hyperprivops) */
+
+                        /* itc paravirtualization
+                         * vAR.ITC = mAR.ITC + itc_offset
+                         * itc_last is one which was lastly passed to
+                         * the guest OS in order to prevent it from
+                         * going backwords.
+                         */
+                        unsigned long itc_offset;
+                        unsigned long itc_last;
                 };
         };
 };
diff --git a/arch/ia64/include/asm/xen/minstate.h b/arch/ia64/include/asm/xen/minstate.h
index 4d92d9bbda7b..c57fa910f2c9 100644
--- a/arch/ia64/include/asm/xen/minstate.h
+++ b/arch/ia64/include/asm/xen/minstate.h
@@ -1,3 +1,12 @@
+
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING
+/* read ar.itc in advance, and use it before leaving bank 0 */
+#define XEN_ACCOUNT_GET_STAMP           \
+        MOV_FROM_ITC(pUStk, p6, r20, r2);
+#else
+#define XEN_ACCOUNT_GET_STAMP
+#endif
+
 /*
  * DO_SAVE_MIN switches to the kernel stacks (if necessary) and saves
  * the minimum state necessary that allows us to turn psr.ic back
@@ -123,7 +132,7 @@
         ;;                                                                                      \
 .mem.offset 0,0; st8.spill [r16]=r2,16;                                                         \
 .mem.offset 8,0; st8.spill [r17]=r3,16;                                                         \
-        ACCOUNT_GET_STAMP                                                                       \
+        XEN_ACCOUNT_GET_STAMP                                                                   \
         adds r2=IA64_PT_REGS_R16_OFFSET,r1;                                                     \
         ;;                                                                                      \
         EXTRA;                                                                                  \
diff --git a/arch/ia64/include/asm/xen/privop.h b/arch/ia64/include/asm/xen/privop.h
index 71ec7546e100..2261dda578ff 100644
--- a/arch/ia64/include/asm/xen/privop.h
+++ b/arch/ia64/include/asm/xen/privop.h
@@ -55,6 +55,8 @@
 #define XSI_BANK1_R16                   (XSI_BASE + XSI_BANK1_R16_OFS)
 #define XSI_BANKNUM                     (XSI_BASE + XSI_BANKNUM_OFS)
 #define XSI_IHA                         (XSI_BASE + XSI_IHA_OFS)
+#define XSI_ITC_OFFSET                  (XSI_BASE + XSI_ITC_OFFSET_OFS)
+#define XSI_ITC_LAST                    (XSI_BASE + XSI_ITC_LAST_OFS)
 #endif
 
 #ifndef __ASSEMBLY__
diff --git a/arch/ia64/kernel/asm-offsets.c b/arch/ia64/kernel/asm-offsets.c
index 742dbb1d5a4f..af5650169043 100644
--- a/arch/ia64/kernel/asm-offsets.c
+++ b/arch/ia64/kernel/asm-offsets.c
@@ -316,5 +316,7 @@ void foo(void)
         DEFINE_MAPPED_REG_OFS(XSI_BANK1_R16_OFS, bank1_regs[0]);
         DEFINE_MAPPED_REG_OFS(XSI_B0NATS_OFS, vbnat);
         DEFINE_MAPPED_REG_OFS(XSI_B1NATS_OFS, vnat);
+        DEFINE_MAPPED_REG_OFS(XSI_ITC_OFFSET_OFS, itc_offset);
+        DEFINE_MAPPED_REG_OFS(XSI_ITC_LAST_OFS, itc_last);
 #endif /* CONFIG_XEN */
 }
diff --git a/arch/ia64/xen/xen_pv_ops.c b/arch/ia64/xen/xen_pv_ops.c
index fe72308321b6..d91336114344 100644
--- a/arch/ia64/xen/xen_pv_ops.c
+++ b/arch/ia64/xen/xen_pv_ops.c
@@ -183,6 +183,75 @@ struct pv_fsys_data xen_fsys_data __initdata = {
  * intrinsics hooks.
  */
 
+static void
+xen_set_itm_with_offset(unsigned long val)
+{
+        /* ia64_cpu_local_tick() calls this with interrupt enabled. */
+        /* WARN_ON(!irqs_disabled()); */
+        xen_set_itm(val - XEN_MAPPEDREGS->itc_offset);
+}
+
+static unsigned long
+xen_get_itm_with_offset(void)
+{
+        /* unused at this moment */
+        printk(KERN_DEBUG "%s is called.\n", __func__);
+
+        WARN_ON(!irqs_disabled());
+        return ia64_native_getreg(_IA64_REG_CR_ITM) +
+                XEN_MAPPEDREGS->itc_offset;
+}
+
+/* ia64_set_itc() is only called by
+ * cpu_init() with ia64_set_itc(0) and ia64_sync_itc().
+ * So XEN_MAPPEDRESG->itc_offset cal be considered as almost constant.
+ */
+static void
+xen_set_itc(unsigned long val)
+{
+        unsigned long mitc;
+
+        WARN_ON(!irqs_disabled());
+        mitc = ia64_native_getreg(_IA64_REG_AR_ITC);
+        XEN_MAPPEDREGS->itc_offset = val - mitc;
+        XEN_MAPPEDREGS->itc_last = val;
+}
+
+static unsigned long
+xen_get_itc(void)
+{
+        unsigned long res;
+        unsigned long itc_offset;
+        unsigned long itc_last;
+        unsigned long ret_itc_last;
+
+        itc_offset = XEN_MAPPEDREGS->itc_offset;
+        do {
+                itc_last = XEN_MAPPEDREGS->itc_last;
+                res = ia64_native_getreg(_IA64_REG_AR_ITC);
+                res += itc_offset;
+                if (itc_last >= res)
+                        res = itc_last + 1;
+                ret_itc_last = cmpxchg(&XEN_MAPPEDREGS->itc_last,
+                                       itc_last, res);
+        } while (unlikely(ret_itc_last != itc_last));
+        return res;
+
+#if 0
+        /* ia64_itc_udelay() calls ia64_get_itc() with interrupt enabled.
+           Should it be paravirtualized instead? */
+        WARN_ON(!irqs_disabled());
+        itc_offset = XEN_MAPPEDREGS->itc_offset;
+        itc_last = XEN_MAPPEDREGS->itc_last;
+        res = ia64_native_getreg(_IA64_REG_AR_ITC);
+        res += itc_offset;
+        if (itc_last >= res)
+                res = itc_last + 1;
+        XEN_MAPPEDREGS->itc_last = res;
+        return res;
+#endif
+}
+
 static void xen_setreg(int regnum, unsigned long val)
 {
         switch (regnum) {
@@ -194,11 +263,14 @@ static void xen_setreg(int regnum, unsigned long val)
                 xen_set_eflag(val);
                 break;
 #endif
+        case _IA64_REG_AR_ITC:
+                xen_set_itc(val);
+                break;
         case _IA64_REG_CR_TPR:
                 xen_set_tpr(val);
                 break;
         case _IA64_REG_CR_ITM:
-                xen_set_itm(val);
+                xen_set_itm_with_offset(val);
                 break;
         case _IA64_REG_CR_EOI:
                 xen_eoi(val);
@@ -222,6 +294,12 @@ static unsigned long xen_getreg(int regnum)
                 res = xen_get_eflag();
                 break;
 #endif
+        case _IA64_REG_AR_ITC:
+                res = xen_get_itc();
+                break;
+        case _IA64_REG_CR_ITM:
+                res = xen_get_itm_with_offset();
+                break;
         case _IA64_REG_CR_IVR:
                 res = xen_get_ivr();
                 break;