[PATCH v2 18/26] KVM: arm64: nv: Add trap forwarding for CNTHCTL_EL2

[Marc Zyngier]

Describe the CNTHCTL_EL2 register, and associate it with all the sysregs
it allows to trap.

Reviewed-by: Eric Auger <eric.auger at redhat.com>
Signed-off-by: Marc Zyngier <maz at kernel.org>
---
 arch/arm64/kvm/emulate-nested.c | 50 ++++++++++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c
index 339976764ac5..74b67895c791 100644
--- a/arch/arm64/kvm/emulate-nested.c
+++ b/arch/arm64/kvm/emulate-nested.c
@@ -99,9 +99,11 @@ enum trap_group {
 
 	/*
 	 * Anything after this point requires a callback evaluating a
-	 * complex trap condition. Hopefully we'll never need this...
+	 * complex trap condition. Ugly stuff.
 	 */
 	__COMPLEX_CONDITIONS__,
+	CGT_CNTHCTL_EL1PCTEN = __COMPLEX_CONDITIONS__,
+	CGT_CNTHCTL_EL1PTEN,
 };
 
 static const struct trap_bits coarse_trap_bits[] = {
@@ -365,10 +367,51 @@ static const enum trap_group *coarse_control_combo[] = {
 
 typedef enum trap_behaviour (*complex_condition_check)(struct kvm_vcpu *);
 
+/*
+ * Warning, maximum confusion ahead.
+ *
+ * When E2H=0, CNTHCTL_EL2[1:0] are defined as EL1PCEN:EL1PCTEN
+ * When E2H=1, CNTHCTL_EL2[11:10] are defined as EL1PTEN:EL1PCTEN
+ *
+ * Note the single letter difference? Yet, the bits have the same
+ * function despite a different layout and a different name.
+ *
+ * We don't try to reconcile this mess. We just use the E2H=0 bits
+ * to generate something that is in the E2H=1 format, and live with
+ * it. You're welcome.
+ */
+static u64 get_sanitized_cnthctl(struct kvm_vcpu *vcpu)
+{
+	u64 val = __vcpu_sys_reg(vcpu, CNTHCTL_EL2);
+
+	if (!vcpu_el2_e2h_is_set(vcpu))
+		val = (val & (CNTHCTL_EL1PCEN | CNTHCTL_EL1PCTEN)) << 10;
+
+	return val & ((CNTHCTL_EL1PCEN | CNTHCTL_EL1PCTEN) << 10);
+}
+
+static enum trap_behaviour check_cnthctl_el1pcten(struct kvm_vcpu *vcpu)
+{
+	if (get_sanitized_cnthctl(vcpu) & (CNTHCTL_EL1PCTEN << 10))
+		return BEHAVE_HANDLE_LOCALLY;
+
+	return BEHAVE_FORWARD_ANY;
+}
+
+static enum trap_behaviour check_cnthctl_el1pten(struct kvm_vcpu *vcpu)
+{
+	if (get_sanitized_cnthctl(vcpu) & (CNTHCTL_EL1PCEN << 10))
+		return BEHAVE_HANDLE_LOCALLY;
+
+	return BEHAVE_FORWARD_ANY;
+}
+
 #define CCC(id, fn)				\
 	[id - __COMPLEX_CONDITIONS__] = fn
 
 static const complex_condition_check ccc[] = {
+	CCC(CGT_CNTHCTL_EL1PCTEN, check_cnthctl_el1pcten),
+	CCC(CGT_CNTHCTL_EL1PTEN, check_cnthctl_el1pten),
 };
 
 /*
@@ -870,6 +913,11 @@ static const struct encoding_to_trap_config encoding_to_cgt[] __initconst = {
 	SR_TRAP(SYS_TRBPTR_EL1, 	CGT_MDCR_E2TB),
 	SR_TRAP(SYS_TRBSR_EL1, 		CGT_MDCR_E2TB),
 	SR_TRAP(SYS_TRBTRG_EL1,		CGT_MDCR_E2TB),
+	SR_TRAP(SYS_CNTP_TVAL_EL0,	CGT_CNTHCTL_EL1PTEN),
+	SR_TRAP(SYS_CNTP_CVAL_EL0,	CGT_CNTHCTL_EL1PTEN),
+	SR_TRAP(SYS_CNTP_CTL_EL0,	CGT_CNTHCTL_EL1PTEN),
+	SR_TRAP(SYS_CNTPCT_EL0,		CGT_CNTHCTL_EL1PCTEN),
+	SR_TRAP(SYS_CNTPCTSS_EL0,	CGT_CNTHCTL_EL1PCTEN),
 };
 
 static DEFINE_XARRAY(sr_forward_xa);
-- 
2.34.1