KVM: arm64: nv: Add trap forwarding for ERET and SMC

Honor the trap forwarding bits for both ERET and SMC, using a new
helper that checks for common conditions.

Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Co-developed-by: Jintack Lim <jintack.lim@linaro.org>
Signed-off-by: Jintack Lim <jintack.lim@linaro.org>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240419102935.1935571-7-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>

diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h
index c77d795556e130d0c2ae05be272043e65d1acddb..dbc4e3a67356b018343bed159332f4132fddf196 100644 (file)
--- a/arch/arm64/include/asm/kvm_nested.h
+++ b/arch/arm64/include/asm/kvm_nested.h
@@ -60,6 +60,7 @@ static inline u64 translate_ttbr0_el2_to_ttbr0_el1(u64 ttbr0)
        return ttbr0 & ~GENMASK_ULL(63, 48);
 }
 
+extern bool forward_smc_trap(struct kvm_vcpu *vcpu);
 
 int kvm_init_nv_sysregs(struct kvm *kvm);
 

diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c
index 4697ba41b3a9c7723b862b35d43019f97d0945d2..2d80e81ae65062b7304e06ad299985920dce825d 100644 (file)
--- a/arch/arm64/kvm/emulate-nested.c
+++ b/arch/arm64/kvm/emulate-nested.c
@@ -2117,6 +2117,26 @@ inject:
        return true;
 }
 
+static bool forward_traps(struct kvm_vcpu *vcpu, u64 control_bit)
+{
+       bool control_bit_set;
+
+       if (!vcpu_has_nv(vcpu))
+               return false;
+
+       control_bit_set = __vcpu_sys_reg(vcpu, HCR_EL2) & control_bit;
+       if (!is_hyp_ctxt(vcpu) && control_bit_set) {
+               kvm_inject_nested_sync(vcpu, kvm_vcpu_get_esr(vcpu));
+               return true;
+       }
+       return false;
+}
+
+bool forward_smc_trap(struct kvm_vcpu *vcpu)
+{
+       return forward_traps(vcpu, HCR_TSC);
+}
+
 static u64 kvm_check_illegal_exception_return(struct kvm_vcpu *vcpu, u64 spsr)
 {
        u64 mode = spsr & PSR_MODE_MASK;
@@ -2155,6 +2175,13 @@ void kvm_emulate_nested_eret(struct kvm_vcpu *vcpu)
        u64 spsr, elr, mode;
        bool direct_eret;
 
+       /*
+        * Forward this trap to the virtual EL2 if the virtual
+        * HCR_EL2.NV bit is set and this is coming from !EL2.
+        */
+       if (forward_traps(vcpu, HCR_NV))
+               return;
+
        /*
         * Going through the whole put/load motions is a waste of time
         * if this is a VHE guest hypervisor returning to its own

diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index 15221e481ccd6eb4c48050d2f187a2c923461014..6a88ec024e2f847fc9b52265e413f8ddb3ab7fd9 100644 (file)
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -55,6 +55,13 @@ static int handle_hvc(struct kvm_vcpu *vcpu)
 
 static int handle_smc(struct kvm_vcpu *vcpu)
 {
+       /*
+        * Forward this trapped smc instruction to the virtual EL2 if
+        * the guest has asked for it.
+        */
+       if (forward_smc_trap(vcpu))
+               return 1;
+
        /*
         * "If an SMC instruction executed at Non-secure EL1 is
         * trapped to EL2 because HCR_EL2.TSC is 1, the exception is a