[Xen-devel] [RFC PATCH 02/10] arm64: Add hook to handle guest GICv3 sysreg accesses

[mjaggi@xxxxxxxxxxxxxxxxxx]

From: Manish Jaggi <manish.jaggi@xxxxxxxxxx>

In order to start handling guest access to GICv3 system registers,
let's add a hook that will get called when we trap a system register
access.
This handling code is kept independent of other traps.
Set CONFIG_VGIC_ERRATA to enable this code.

Signed-off-by: Manish Jaggi <manish.jaggi@xxxxxxxxxx>
---
 xen/arch/arm/arm64/vsysreg.c      | 17 +++++++++++++++++
 xen/arch/arm/traps.c              | 11 +++++++++++
 xen/include/asm-arm/arm64/traps.h |  2 ++
 3 files changed, 30 insertions(+)

diff --git a/xen/arch/arm/arm64/vsysreg.c b/xen/arch/arm/arm64/vsysreg.c
index c57ac12503..a5c17e460f 100644
--- a/xen/arch/arm/arm64/vsysreg.c
+++ b/xen/arch/arm/arm64/vsysreg.c
@@ -219,6 +219,23 @@ void do_sysreg(struct cpu_user_regs *regs,
     regs->pc += 4;
 }
 
+#ifdef CONFIG_VGIC_ERRATA
+int do_fixup_vgic_errata(struct cpu_user_regs *regs, const union hsr hsr)
+{
+    int ret = 0;
+
+    local_irq_disable();
+    switch ( hsr.bits & HSR_SYSREG_REGS_MASK )
+    {
+    default:
+        ret = -1;
+        break;
+    }
+    local_irq_enable();
+
+    return ret;
+}
+#endif
 /*
  * Local variables:
  * mode: C
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index f6f6de3691..d4f0581d33 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -2103,6 +2103,17 @@ void do_trap_guest_sync(struct cpu_user_regs *regs)
 {
     const union hsr hsr = { .bits = regs->hsr };
 
+#ifdef CONFIG_VGIC_ERRATA
+    int ret;
+
+    ret  = do_fixup_vgic_errata(regs,hsr);
+    if ( !ret )
+    {
+        advance_pc(regs, hsr);
+        return;
+    }
+#endif
+
     enter_hypervisor_head(regs);
 
     switch (hsr.ec) {
diff --git a/xen/include/asm-arm/arm64/traps.h 
b/xen/include/asm-arm/arm64/traps.h
index 2379b578cb..7378a1b022 100644
--- a/xen/include/asm-arm/arm64/traps.h
+++ b/xen/include/asm-arm/arm64/traps.h
@@ -5,6 +5,8 @@ void inject_undef64_exception(struct cpu_user_regs *regs, int 
instr_len);
 
 void do_sysreg(struct cpu_user_regs *regs,
                const union hsr hsr);
+int do_fixup_vgic_errata(struct cpu_user_regs *regs,
+               const union hsr hsr);
 
 #endif /* __ASM_ARM64_TRAPS__ */
 /*
-- 
2.14.1


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