[Xen-devel] [PATCH v2 15/17] arm: Hook workaround handler from traps.c based on Cavium workaround_30115

[Manish Jaggi <manish.jaggi@xxxxxxxxxx>]

Function vgic_v3_handle_cpuif_access is called from do_trap_guest_sync
if ARM64_WORKAROUND_CAVIUM_30115 capability is found.

A flag skip_hyp_tail is introduced in struct cpu_info. This flag
is used to skip leave_hypervisor_tail when enter_hypervisor_head
is not invoked. enter_hypervisor_head andleave_hypervisor_tail are
invoked in sync, if one is not called other one should be skipped,
otherwise guest vGIC state be out-of-date.

Signed-off-by: Manish Jaggi <manish.jaggi@xxxxxxxxxx>
---
 xen/arch/arm/arm64/Makefile   |  1 +
 xen/arch/arm/traps.c          | 31 +++++++++++++++++++++++++++++++
 xen/include/asm-arm/current.h |  3 ++-
 3 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/arm64/Makefile b/xen/arch/arm/arm64/Makefile
index 718fe44455..eed3c9e913 100644
--- a/xen/arch/arm/arm64/Makefile
+++ b/xen/arch/arm/arm64/Makefile
@@ -11,3 +11,4 @@ obj-y += smpboot.o
 obj-y += traps.o
 obj-y += vfp.o
 obj-y += vsysreg.o
+obj-$(CONFIG_CAVIUM_ERRATUM_30115) += vgic-v3-sr.o
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index f6f6de3691..1dc34275b3 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -2103,6 +2103,27 @@ void do_trap_guest_sync(struct cpu_user_regs *regs)
 {
     const union hsr hsr = { .bits = regs->hsr };
 
+    if ( check_workaround_cavium_30115() )
+    {
+        if ( vgic_v3_handle_cpuif_access(regs) )
+        {
+               /*
+            * if true, g0/g1 vgic register trap is emulated for errata
+                * so rest of handling of do_trap_guest_sync is not required.
+                */
+            advance_pc(regs, hsr);
+            /*
+             * enter_hypervisor_head is not invoked when workaround 30115
+             * is in place. enter_hypervisor_head and leave_hypervisor_tail
+             * are invoked in sync, if one is not called other one should be
+             * skipped, otherwise guest vGIC state be out-of-date.
+             */
+            get_cpu_info()->skip_hyp_tail = true;
+
+            return;
+        }
+    }
+
     enter_hypervisor_head(regs);
 
     switch (hsr.ec) {
@@ -2295,6 +2316,16 @@ void do_trap_fiq(struct cpu_user_regs *regs)
 
 void leave_hypervisor_tail(void)
 {
+    /*
+     * if skip_hyp_tail is set simply retrun;
+     */
+    if ( unlikely(get_cpu_info()->skip_hyp_tail) )
+    {
+        /* clear it, so that it is false when not handling g0/g1 traps */
+        get_cpu_info()->skip_hyp_tail = false;
+        return;
+    }
+
     while (1)
     {
         local_irq_disable();
diff --git a/xen/include/asm-arm/current.h b/xen/include/asm-arm/current.h
index 7a0971fdea..63b7e68f0b 100644
--- a/xen/include/asm-arm/current.h
+++ b/xen/include/asm-arm/current.h
@@ -21,7 +21,14 @@ DECLARE_PER_CPU(struct vcpu *, curr_vcpu);
 struct cpu_info {
     struct cpu_user_regs guest_cpu_user_regs;
     unsigned long elr;
-    unsigned int pad;
+/*
+ * Flag is used to skip leave_hypervisor_tail when enter_hypervisor_head
+ * is not invoked. enter_hypervisor_head andleave_hypervisor_tail are
+ * invoked in sync, if one is not called other one should be skipped,
+ * otherwise guest vGIC state be out-of-date.
+ */
+    bool skip_hyp_tail:1;
+    unsigned int pad:31;
 };
 
 static inline struct cpu_info *get_cpu_info(void)
-- 
2.14.1


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