[Xen-devel] [PATCH] xen/arm: Trap the ACTLR register

[Julien Grall <julien.grall@xxxxxxxxxx>]

On Cortex-A15 ACTLR is used to set the SMP bit. If the guest has the control on
this register, it can disable SMP support and so TLB broadcast.

Implement the access to ACTRL as read-only register with SMP bit set to one
if the guest has multiple VCPUs.

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
---
 xen/arch/arm/domain.c |    9 +++++++--
 xen/arch/arm/traps.c  |    8 +++++++-
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index f465ab7..6937abf 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -28,6 +28,7 @@
 #include <asm/irq.h>
 #include <asm/cpufeature.h>
 #include <asm/vfp.h>
+#include <asm/processor-ca15.h>
 
 #include <asm/gic.h>
 #include "vtimer.h"
@@ -61,7 +62,6 @@ static void ctxt_switch_from(struct vcpu *p)
     p->arch.csselr = READ_SYSREG(CSSELR_EL1);
 
     /* Control Registers */
-    p->arch.actlr = READ_SYSREG(ACTLR_EL1);
     p->arch.sctlr = READ_SYSREG(SCTLR_EL1);
     p->arch.cpacr = READ_SYSREG(CPACR_EL1);
 
@@ -182,7 +182,6 @@ static void ctxt_switch_to(struct vcpu *n)
     isb();
 
     /* Control Registers */
-    WRITE_SYSREG(n->arch.actlr, ACTLR_EL1);
     WRITE_SYSREG(n->arch.sctlr, SCTLR_EL1);
     WRITE_SYSREG(n->arch.cpacr, CPACR_EL1);
 
@@ -452,6 +451,12 @@ int vcpu_initialise(struct vcpu *v)
         return rc;
 
     v->arch.sctlr = SCTLR_BASE;
+    v->arch.actlr = READ_SYSREG32(ACTLR_EL1);
+    /* XXX: Handle other than CA15 cpus */
+    if ( v->domain->max_vcpus > 1 )
+        v->arch.actlr |= ACTLR_CA15_SMP;
+    else
+        v->arch.actlr &= ~ACTLR_CA15_SMP;
 
     if ( (rc = vcpu_vgic_init(v)) != 0 )
         return rc;
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 398d209..bbd60aa 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -62,7 +62,8 @@ void __cpuinit init_traps(void)
     WRITE_SYSREG((vaddr_t)hyp_traps_vector, VBAR_EL2);
 
     /* Setup hypervisor traps */
-    WRITE_SYSREG(HCR_PTW|HCR_BSU_OUTER|HCR_AMO|HCR_IMO|HCR_VM|HCR_TWI|HCR_TSC, 
HCR_EL2);
+    WRITE_SYSREG(HCR_PTW|HCR_BSU_OUTER|HCR_AMO|HCR_IMO|HCR_VM|HCR_TWI|HCR_TSC|
+                 HCR_TAC, HCR_EL2);
     isb();
 }
 
@@ -836,6 +837,7 @@ static void do_cp15_32(struct cpu_user_regs *regs,
 {
     struct hsr_cp32 cp32 = hsr.cp32;
     uint32_t *r = (uint32_t*)select_user_reg(regs, cp32.reg);
+    struct vcpu *v = current;
 
     if ( !cp32.ccvalid ) {
         dprintk(XENLOG_ERR, "cp_15(32): need to handle invalid condition 
codes\n");
@@ -889,6 +891,10 @@ static void do_cp15_32(struct cpu_user_regs *regs,
             domain_crash_synchronous();
         }
         break;
+    case HSR_CPREG32(ACTLR):
+        if ( cp32.read )
+           *r = v->arch.actlr;
+        break;
     default:
         printk("%s p15, %d, r%d, cr%d, cr%d, %d @ 0x%"PRIregister"\n",
                cp32.read ? "mrc" : "mcr",
-- 
1.7.10.4


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