xen/arm: do_trap_hypervisor: Separate hypervisor and guest traps

The function do_trap_hypervisor is currently handling both trap coming
from the hypervisor and the guest. This makes difficult to get specific
behavior when a trap is coming from either the guest or the hypervisor.

Split the function into two parts:
    - do_trap_guest_sync to handle guest traps
    - do_trap_hyp_sync to handle hypervisor traps

On AArch32, the Hyp Trap Exception provides the standard mechanism for
trapping Guest OS functions to the hypervisor (see B1.14.1 in ARM DDI
0406C.c). It cannot be generated when generated when the processor is in
Hyp Mode, instead other exception will be used. So it is fine to replace
the call to do_trap_hypervisor by do_trap_guest_sync.

For AArch64, there are two distincts exception depending whether the
exception was taken from the current level (hypervisor) or lower level
(guest).

Note that the unknown traps from guests will lead to panic Xen. This is
already behavior and is left unchanged for simplicy. A follow-up patch
will address that.

Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
master-commit-id: 5a0ed9a09ebb32b620d9217875bb5206d5ccf4d7

diff --git a/xen/arch/arm/arm32/entry.S b/xen/arch/arm/arm32/entry.S
index d7cd06ca38e34fabc9993e4f6f2e55f95050de50..090f04947027140ace991e52393959fb6ff16357 100644 (file)
--- a/xen/arch/arm/arm32/entry.S
+++ b/xen/arch/arm/arm32/entry.S
@@ -130,7 +130,7 @@ GLOBAL(hyp_traps_vector)
         b trap_supervisor_call          /* 0x08 - Supervisor Call */
         b trap_prefetch_abort           /* 0x0c - Prefetch Abort */
         b trap_data_abort               /* 0x10 - Data Abort */
-        b trap_hypervisor               /* 0x14 - Hypervisor */
+        b trap_guest_sync               /* 0x14 - Hypervisor */
         b trap_irq                      /* 0x18 - IRQ */
         b trap_fiq                      /* 0x1c - FIQ */
 
@@ -138,7 +138,7 @@ DEFINE_TRAP_ENTRY(undefined_instruction)
 DEFINE_TRAP_ENTRY(supervisor_call)
 DEFINE_TRAP_ENTRY(prefetch_abort)
 DEFINE_TRAP_ENTRY(data_abort)
-DEFINE_TRAP_ENTRY(hypervisor)
+DEFINE_TRAP_ENTRY(guest_sync)
 DEFINE_TRAP_ENTRY_NOIRQ(irq)
 DEFINE_TRAP_ENTRY_NOIRQ(fiq)
 

diff --git a/xen/arch/arm/arm64/entry.S b/xen/arch/arm/arm64/entry.S
index 66ba0cb4fa9941cb3ed57f10bcddd97b133531f0..0e7ddde9edc0eb8579b3643e21d19b0e0c7ff92e 100644 (file)
--- a/xen/arch/arm/arm64/entry.S
+++ b/xen/arch/arm/arm64/entry.S
@@ -219,7 +219,7 @@ hyp_sync:
         entry   hyp=1
         msr     daifclr, #2
         mov     x0, sp
-        bl      do_trap_hypervisor
+        bl      do_trap_hyp_sync
         exit    hyp=1
 
 hyp_irq:
@@ -238,7 +238,7 @@ guest_sync:
         cbnz    x0, 1f
         msr     daifclr, #2
         mov     x0, sp
-        bl      do_trap_hypervisor
+        bl      do_trap_guest_sync
 1:
         exit    hyp=0, compat=0
 
@@ -276,7 +276,7 @@ guest_sync_compat:
         cbnz    x0, 1f
         msr     daifclr, #2
         mov     x0, sp
-        bl      do_trap_hypervisor
+        bl      do_trap_guest_sync
 1:
         exit    hyp=0, compat=1
 

diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 40805de44dd2cddf1681527f4eb9fdb59b715f18..518a36e6e509dc38d2e42bdad04313023686a2d4 100644 (file)
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -2657,7 +2657,7 @@ static void enter_hypervisor_head(struct cpu_user_regs *regs)
         gic_clear_lrs(current);
 }
 
-asmlinkage void do_trap_hypervisor(struct cpu_user_regs *regs)
+asmlinkage void do_trap_guest_sync(struct cpu_user_regs *regs)
 {
     const union hsr hsr = { .bits = regs->hsr };
 
@@ -2777,6 +2777,21 @@ asmlinkage void do_trap_hypervisor(struct cpu_user_regs *regs)
         do_trap_data_abort_guest(regs, hsr);
         break;
 
+    default:
+        printk("Unknown Guest Trap. HSR=0x%x EC=0x%x IL=%x Syndrome=0x%"PRIx32"\n",
+               hsr.bits, hsr.ec, hsr.len, hsr.iss);
+        do_unexpected_trap("Guest", regs);
+    }
+}
+
+asmlinkage void do_trap_hyp_sync(struct cpu_user_regs *regs)
+{
+    const union hsr hsr = { .bits = regs->hsr };
+
+    enter_hypervisor_head(regs);
+
+    switch ( hsr.ec )
+    {
 #ifdef CONFIG_ARM_64
     case HSR_EC_BRK:
         do_trap_brk(regs, hsr);