Re: [PATCH v4 23/28] KVM: arm64: nv: Add SVC trap forwarding

HFGITR_EL2 allows the trap of SVC instructions to EL2. Allow these
traps to be forwarded. Take this opportunity to deny any 32bit activity
when NV is enabled.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/arm.c         |  4 ++++
 arch/arm64/kvm/handle_exit.c | 12 ++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 72dc53a75d1c..8b51570a76f8 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c

@@ -36,6 +36,7 @@
 #include <asm/kvm_arm.h>
 #include <asm/kvm_asm.h>
 #include <asm/kvm_mmu.h>
+#include <asm/kvm_nested.h>
 #include <asm/kvm_pkvm.h>
 #include <asm/kvm_emulate.h>
 #include <asm/sections.h>

@@ -818,6 +819,9 @@ static bool vcpu_mode_is_bad_32bit(struct kvm_vcpu *vcpu)
        if (likely(!vcpu_mode_is_32bit(vcpu)))
                return false;

+       if (vcpu_has_nv(vcpu))
+               return true;
+
        return !kvm_supports_32bit_el0();
 }

diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index 6dcd6604b6bc..3b86d534b995 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c

@@ -226,6 +226,17 @@ static int kvm_handle_eret(struct kvm_vcpu *vcpu)
        return 1;
 }

+static int handle_svc(struct kvm_vcpu *vcpu)
+{
+       /*
+        * So far, SVC traps only for NV via HFGITR_EL2. A SVC from a
+        * 32bit guest would be caught by vpcu_mode_is_bad_32bit(), so
+        * we should only have to deal with a 64 bit exception.
+        */
+       kvm_inject_nested_sync(vcpu, kvm_vcpu_get_esr(vcpu));
+       return 1;
+}
+
 static exit_handle_fn arm_exit_handlers[] = {
        [0 ... ESR_ELx_EC_MAX]  = kvm_handle_unknown_ec,
        [ESR_ELx_EC_WFx]        = kvm_handle_wfx,

@@ -239,6 +250,7 @@ static exit_handle_fn arm_exit_handlers[] = {
        [ESR_ELx_EC_SMC32]      = handle_smc,
        [ESR_ELx_EC_HVC64]      = handle_hvc,
        [ESR_ELx_EC_SMC64]      = handle_smc,
+       [ESR_ELx_EC_SVC64]      = handle_svc,
        [ESR_ELx_EC_SYS64]      = kvm_handle_sys_reg,
        [ESR_ELx_EC_SVE]        = handle_sve,
        [ESR_ELx_EC_ERET]       = kvm_handle_eret,
--

2.34.1