ARM: KVM: trap VM system registers until MMU and caches are ON

In order to be able to detect the point where the guest enables
its MMU and caches, trap all the VM related system registers.

Once we see the guest enabling both the MMU and the caches, we
can go back to a saner mode of operation, which is to leave these
registers in complete control of the guest.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>

1 files changed, 58 insertions, 16 deletions

diff --git a/arch/arm/kvm/coproc.c b/arch/arm/kvm/coproc.c
index a5a54a48d51b..c58a35116f63 100644
--- a/arch/arm/kvm/coproc.c
+++ b/arch/arm/kvm/coproc.c
@@ -23,6 +23,7 @@
 #include <asm/kvm_host.h>
 #include <asm/kvm_emulate.h>
 #include <asm/kvm_coproc.h>
+#include <asm/kvm_mmu.h>
 #include <asm/cacheflush.h>
 #include <asm/cputype.h>
 #include <trace/events/kvm.h>
@@ -205,6 +206,44 @@ done:
 }
 
 /*
+ * Generic accessor for VM registers. Only called as long as HCR_TVM
+ * is set.
+ */
+static bool access_vm_reg(struct kvm_vcpu *vcpu,
+			  const struct coproc_params *p,
+			  const struct coproc_reg *r)
+{
+	BUG_ON(!p->is_write);
+
+	vcpu->arch.cp15[r->reg] = *vcpu_reg(vcpu, p->Rt1);
+	if (p->is_64bit)
+		vcpu->arch.cp15[r->reg + 1] = *vcpu_reg(vcpu, p->Rt2);
+
+	return true;
+}
+
+/*
+ * SCTLR accessor. Only called as long as HCR_TVM is set.  If the
+ * guest enables the MMU, we stop trapping the VM sys_regs and leave
+ * it in complete control of the caches.
+ *
+ * Used by the cpu-specific code.
+ */
+bool access_sctlr(struct kvm_vcpu *vcpu,
+		  const struct coproc_params *p,
+		  const struct coproc_reg *r)
+{
+	access_vm_reg(vcpu, p, r);
+
+	if (vcpu_has_cache_enabled(vcpu)) {	/* MMU+Caches enabled? */
+		vcpu->arch.hcr &= ~HCR_TVM;
+		stage2_flush_vm(vcpu->kvm);
+	}
+
+	return true;
+}
+
+/*
  * We could trap ID_DFR0 and tell the guest we don't support performance
  * monitoring.  Unfortunately the patch to make the kernel check ID_DFR0 was
  * NAKed, so it will read the PMCR anyway.
@@ -261,33 +300,36 @@ static const struct coproc_reg cp15_regs[] = {
 	{ CRn( 1), CRm( 0), Op1( 0), Op2( 2), is32,
 			NULL, reset_val, c1_CPACR, 0x00000000 },
 
-	/* TTBR0/TTBR1: swapped by interrupt.S. */
-	{ CRm64( 2), Op1( 0), is64, NULL, reset_unknown64, c2_TTBR0 },
-	{ CRm64( 2), Op1( 1), is64, NULL, reset_unknown64, c2_TTBR1 },
-
-	/* TTBCR: swapped by interrupt.S. */
+	/* TTBR0/TTBR1/TTBCR: swapped by interrupt.S. */
+	{ CRm64( 2), Op1( 0), is64, access_vm_reg, reset_unknown64, c2_TTBR0 },
+	{ CRn(2), CRm( 0), Op1( 0), Op2( 0), is32,
+			access_vm_reg, reset_unknown, c2_TTBR0 },
+	{ CRn(2), CRm( 0), Op1( 0), Op2( 1), is32,
+			access_vm_reg, reset_unknown, c2_TTBR1 },
 	{ CRn( 2), CRm( 0), Op1( 0), Op2( 2), is32,
-			NULL, reset_val, c2_TTBCR, 0x00000000 },
+			access_vm_reg, reset_val, c2_TTBCR, 0x00000000 },
+	{ CRm64( 2), Op1( 1), is64, access_vm_reg, reset_unknown64, c2_TTBR1 },
+
 
 	/* DACR: swapped by interrupt.S. */
 	{ CRn( 3), CRm( 0), Op1( 0), Op2( 0), is32,
-			NULL, reset_unknown, c3_DACR },
+			access_vm_reg, reset_unknown, c3_DACR },
 
 	/* DFSR/IFSR/ADFSR/AIFSR: swapped by interrupt.S. */
 	{ CRn( 5), CRm( 0), Op1( 0), Op2( 0), is32,
-			NULL, reset_unknown, c5_DFSR },
+			access_vm_reg, reset_unknown, c5_DFSR },
 	{ CRn( 5), CRm( 0), Op1( 0), Op2( 1), is32,
-			NULL, reset_unknown, c5_IFSR },
+			access_vm_reg, reset_unknown, c5_IFSR },
 	{ CRn( 5), CRm( 1), Op1( 0), Op2( 0), is32,
-			NULL, reset_unknown, c5_ADFSR },
+			access_vm_reg, reset_unknown, c5_ADFSR },
 	{ CRn( 5), CRm( 1), Op1( 0), Op2( 1), is32,
-			NULL, reset_unknown, c5_AIFSR },
+			access_vm_reg, reset_unknown, c5_AIFSR },
 
 	/* DFAR/IFAR: swapped by interrupt.S. */
 	{ CRn( 6), CRm( 0), Op1( 0), Op2( 0), is32,
-			NULL, reset_unknown, c6_DFAR },
+			access_vm_reg, reset_unknown, c6_DFAR },
 	{ CRn( 6), CRm( 0), Op1( 0), Op2( 2), is32,
-			NULL, reset_unknown, c6_IFAR },
+			access_vm_reg, reset_unknown, c6_IFAR },
 
 	/* PAR swapped by interrupt.S */
 	{ CRm64( 7), Op1( 0), is64, NULL, reset_unknown64, c7_PAR },
@@ -324,9 +366,9 @@ static const struct coproc_reg cp15_regs[] = {
 
 	/* PRRR/NMRR (aka MAIR0/MAIR1): swapped by interrupt.S. */
 	{ CRn(10), CRm( 2), Op1( 0), Op2( 0), is32,
-			NULL, reset_unknown, c10_PRRR},
+			access_vm_reg, reset_unknown, c10_PRRR},
 	{ CRn(10), CRm( 2), Op1( 0), Op2( 1), is32,
-			NULL, reset_unknown, c10_NMRR},
+			access_vm_reg, reset_unknown, c10_NMRR},
 
 	/* AMAIR0/AMAIR1: swapped by interrupt.S. */
 	{ CRn(10), CRm( 3), Op1( 0), Op2( 0), is32,
@@ -340,7 +382,7 @@ static const struct coproc_reg cp15_regs[] = {
 
 	/* CONTEXTIDR/TPIDRURW/TPIDRURO/TPIDRPRW: swapped by interrupt.S. */
 	{ CRn(13), CRm( 0), Op1( 0), Op2( 1), is32,
-			NULL, reset_val, c13_CID, 0x00000000 },
+			access_vm_reg, reset_val, c13_CID, 0x00000000 },
 	{ CRn(13), CRm( 0), Op1( 0), Op2( 2), is32,
 			NULL, reset_unknown, c13_TID_URW },
 	{ CRn(13), CRm( 0), Op1( 0), Op2( 3), is32,