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KVM: arm64: Move early handlers to per-EC handlers

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Simplify the early exception handling by slicing the gigantic decoding
tree into a more manageable set of functions, similar to what we have
in handle_exit.c.

This will also make the structure reusable for pKVM's own early exit
handling.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Fuad Tabba <tabba@google.com>
Link: https://lore.kernel.org/r/20211010145636.1950948-4-tabba@google.com
This commit is contained in:
Marc Zyngier 2021-10-10 15:56:28 +01:00
parent cc1e6fdfa9
commit 8fb2046180
3 changed files with 124 additions and 68 deletions
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160
arch/arm64/kvm/hyp/include/hyp/switch.h
View File

@ -136,16 +136,7 @@ static inline void ___deactivate_traps(struct kvm_vcpu *vcpu)
static inline bool __populate_fault_info(struct kvm_vcpu *vcpu)
{
u8 ec;
u64 esr;
esr = vcpu->arch.fault.esr_el2;
ec = ESR_ELx_EC(esr);
if (ec != ESR_ELx_EC_DABT_LOW && ec != ESR_ELx_EC_IABT_LOW)
return true;
return __get_fault_info(esr, &vcpu->arch.fault);
return __get_fault_info(vcpu->arch.fault.esr_el2, &vcpu->arch.fault);
}
static inline void __hyp_sve_save_host(struct kvm_vcpu *vcpu)
@ -166,8 +157,13 @@ static inline void __hyp_sve_restore_guest(struct kvm_vcpu *vcpu)
write_sysreg_el1(__vcpu_sys_reg(vcpu, ZCR_EL1), SYS_ZCR);
}
/* Check for an FPSIMD/SVE trap and handle as appropriate */
static inline bool __hyp_handle_fpsimd(struct kvm_vcpu *vcpu)
/*
* We trap the first access to the FP/SIMD to save the host context and
* restore the guest context lazily.
* If FP/SIMD is not implemented, handle the trap and inject an undefined
* instruction exception to the guest. Similarly for trapped SVE accesses.
*/
static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
{
bool sve_guest, sve_host;
u8 esr_ec;
@ -185,9 +181,6 @@ static inline bool __hyp_handle_fpsimd(struct kvm_vcpu *vcpu)
}
esr_ec = kvm_vcpu_trap_get_class(vcpu);
if (esr_ec != ESR_ELx_EC_FP_ASIMD &&
esr_ec != ESR_ELx_EC_SVE)
return false;
/* Don't handle SVE traps for non-SVE vcpus here: */
if (!sve_guest && esr_ec != ESR_ELx_EC_FP_ASIMD)
@ -325,7 +318,7 @@ static inline bool esr_is_ptrauth_trap(u32 esr)
DECLARE_PER_CPU(struct kvm_cpu_context, kvm_hyp_ctxt);
static inline bool __hyp_handle_ptrauth(struct kvm_vcpu *vcpu)
static bool kvm_hyp_handle_ptrauth(struct kvm_vcpu *vcpu, u64 *exit_code)
{
struct kvm_cpu_context *ctxt;
u64 val;
@ -350,6 +343,87 @@ static inline bool __hyp_handle_ptrauth(struct kvm_vcpu *vcpu)
return true;
}
static bool kvm_hyp_handle_sysreg(struct kvm_vcpu *vcpu, u64 *exit_code)
{
if (cpus_have_final_cap(ARM64_WORKAROUND_CAVIUM_TX2_219_TVM) &&
handle_tx2_tvm(vcpu))
return true;
if (static_branch_unlikely(&vgic_v3_cpuif_trap) &&
__vgic_v3_perform_cpuif_access(vcpu) == 1)
return true;
return false;
}
static bool kvm_hyp_handle_cp15_32(struct kvm_vcpu *vcpu, u64 *exit_code)
{
if (static_branch_unlikely(&vgic_v3_cpuif_trap) &&
__vgic_v3_perform_cpuif_access(vcpu) == 1)
return true;
return false;
}
static bool kvm_hyp_handle_iabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
{
if (!__populate_fault_info(vcpu))
return true;
return false;
}
static bool kvm_hyp_handle_dabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
{
if (!__populate_fault_info(vcpu))
return true;
if (static_branch_unlikely(&vgic_v2_cpuif_trap)) {
bool valid;
valid = kvm_vcpu_trap_get_fault_type(vcpu) == FSC_FAULT &&
kvm_vcpu_dabt_isvalid(vcpu) &&
!kvm_vcpu_abt_issea(vcpu) &&
!kvm_vcpu_abt_iss1tw(vcpu);
if (valid) {
int ret = __vgic_v2_perform_cpuif_access(vcpu);
if (ret == 1)
return true;
/* Promote an illegal access to an SError.*/
if (ret == -1)
*exit_code = ARM_EXCEPTION_EL1_SERROR;
}
}
return false;
}
typedef bool (*exit_handler_fn)(struct kvm_vcpu *, u64 *);
static const exit_handler_fn *kvm_get_exit_handler_array(void);
/*
* Allow the hypervisor to handle the exit with an exit handler if it has one.
*
* Returns true if the hypervisor handled the exit, and control should go back
* to the guest, or false if it hasn't.
*/
static inline bool kvm_hyp_handle_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
{
const exit_handler_fn *handlers = kvm_get_exit_handler_array();
exit_handler_fn fn;
fn = handlers[kvm_vcpu_trap_get_class(vcpu)];
if (fn)
return fn(vcpu, exit_code);
return false;
}
/*
* Return true when we were able to fixup the guest exit and should return to
* the guest, false when we should restore the host state and return to the
@ -384,59 +458,9 @@ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
if (*exit_code != ARM_EXCEPTION_TRAP)
goto exit;
if (cpus_have_final_cap(ARM64_WORKAROUND_CAVIUM_TX2_219_TVM) &&
kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_SYS64 &&
handle_tx2_tvm(vcpu))
/* Check if there's an exit handler and allow it to handle the exit. */
if (kvm_hyp_handle_exit(vcpu, exit_code))
goto guest;
/*
* We trap the first access to the FP/SIMD to save the host context
* and restore the guest context lazily.
* If FP/SIMD is not implemented, handle the trap and inject an
* undefined instruction exception to the guest.
* Similarly for trapped SVE accesses.
*/
if (__hyp_handle_fpsimd(vcpu))
goto guest;
if (__hyp_handle_ptrauth(vcpu))
goto guest;
if (!__populate_fault_info(vcpu))
goto guest;
if (static_branch_unlikely(&vgic_v2_cpuif_trap)) {
bool valid;
valid = kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_DABT_LOW &&
kvm_vcpu_trap_get_fault_type(vcpu) == FSC_FAULT &&
kvm_vcpu_dabt_isvalid(vcpu) &&
!kvm_vcpu_abt_issea(vcpu) &&
!kvm_vcpu_abt_iss1tw(vcpu);
if (valid) {
int ret = __vgic_v2_perform_cpuif_access(vcpu);
if (ret == 1)
goto guest;
/* Promote an illegal access to an SError.*/
if (ret == -1)
*exit_code = ARM_EXCEPTION_EL1_SERROR;
goto exit;
}
}
if (static_branch_unlikely(&vgic_v3_cpuif_trap) &&
(kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_SYS64 ||
kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_CP15_32)) {
int ret = __vgic_v3_perform_cpuif_access(vcpu);
if (ret == 1)
goto guest;
}
exit:
/* Return to the host kernel and handle the exit */
return false;

16
arch/arm64/kvm/hyp/nvhe/switch.c
View File

@ -158,6 +158,22 @@ static void __pmu_switch_to_host(struct kvm_cpu_context *host_ctxt)
write_sysreg(pmu->events_host, pmcntenset_el0);
}
static const exit_handler_fn hyp_exit_handlers[] = {
[0 ... ESR_ELx_EC_MAX] = NULL,
[ESR_ELx_EC_CP15_32] = kvm_hyp_handle_cp15_32,
[ESR_ELx_EC_SYS64] = kvm_hyp_handle_sysreg,
[ESR_ELx_EC_SVE] = kvm_hyp_handle_fpsimd,
[ESR_ELx_EC_FP_ASIMD] = kvm_hyp_handle_fpsimd,
[ESR_ELx_EC_IABT_LOW] = kvm_hyp_handle_iabt_low,
[ESR_ELx_EC_DABT_LOW] = kvm_hyp_handle_dabt_low,
[ESR_ELx_EC_PAC] = kvm_hyp_handle_ptrauth,
};
static const exit_handler_fn *kvm_get_exit_handler_array(void)
{
return hyp_exit_handlers;
}
/* Switch to the guest for legacy non-VHE systems */
int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
{

16
arch/arm64/kvm/hyp/vhe/switch.c
View File

@ -96,6 +96,22 @@ void deactivate_traps_vhe_put(struct kvm_vcpu *vcpu)
__deactivate_traps_common(vcpu);
}
static const exit_handler_fn hyp_exit_handlers[] = {
[0 ... ESR_ELx_EC_MAX] = NULL,
[ESR_ELx_EC_CP15_32] = kvm_hyp_handle_cp15_32,
[ESR_ELx_EC_SYS64] = kvm_hyp_handle_sysreg,
[ESR_ELx_EC_SVE] = kvm_hyp_handle_fpsimd,
[ESR_ELx_EC_FP_ASIMD] = kvm_hyp_handle_fpsimd,
[ESR_ELx_EC_IABT_LOW] = kvm_hyp_handle_iabt_low,
[ESR_ELx_EC_DABT_LOW] = kvm_hyp_handle_dabt_low,
[ESR_ELx_EC_PAC] = kvm_hyp_handle_ptrauth,
};
static const exit_handler_fn *kvm_get_exit_handler_array(void)
{
return hyp_exit_handlers;
}
/* Switch to the guest for VHE systems running in EL2 */
static int __kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
{