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KVM: arm64: Refactor exit handlers

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The hyp exit handling logic is largely shared between VHE and nVHE/hVHE,
with common logic in arch/arm64/kvm/hyp/include/hyp/switch.h. The code
in the header depends on function definitions provided by
arch/arm64/kvm/hyp/vhe/switch.c and arch/arm64/kvm/hyp/nvhe/switch.c
when they include the header.

This is an unusual header dependency, and prevents the use of
arch/arm64/kvm/hyp/include/hyp/switch.h in other files as this would
result in compiler warnings regarding missing definitions, e.g.

| In file included from arch/arm64/kvm/hyp/nvhe/hyp-main.c:8:
| ./arch/arm64/kvm/hyp/include/hyp/switch.h:733:31: warning: 'kvm_get_exit_handler_array' used but never defined
|   733 | static const exit_handler_fn *kvm_get_exit_handler_array(struct kvm_vcpu *vcpu);
|       |                               ^~~~~~~~~~~~~~~~~~~~~~~~~~
| ./arch/arm64/kvm/hyp/include/hyp/switch.h:735:13: warning: 'early_exit_filter' used but never defined
|   735 | static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code);
|       |             ^~~~~~~~~~~~~~~~~

Refactor the logic such that the header doesn't depend on anything from
the C files. There should be no functional change as a result of this
patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250210195226.1215254-7-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Mark Rutland 2025-02-10 19:52:24 +00:00 • committed by Marc Zyngier
parent ee14db31a9
commit 9b66195063
3 changed files with 26 additions and 41 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

30
arch/arm64/kvm/hyp/include/hyp/switch.h
View file

@ -679,23 +679,16 @@ static bool kvm_hyp_handle_dabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
typedef bool (*exit_handler_fn)(struct kvm_vcpu *, u64 *);
static const exit_handler_fn *kvm_get_exit_handler_array(struct kvm_vcpu *vcpu);
static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code);
/*
* 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)
static inline bool kvm_hyp_handle_exit(struct kvm_vcpu *vcpu, u64 *exit_code,
const exit_handler_fn *handlers)
{
const exit_handler_fn *handlers = kvm_get_exit_handler_array(vcpu);
exit_handler_fn fn;
fn = handlers[kvm_vcpu_trap_get_class(vcpu)];
exit_handler_fn fn = handlers[kvm_vcpu_trap_get_class(vcpu)];
if (fn)
return fn(vcpu, exit_code);
@ -725,20 +718,9 @@ static inline void synchronize_vcpu_pstate(struct kvm_vcpu *vcpu, u64 *exit_code
* the guest, false when we should restore the host state and return to the
* main run loop.
*/
static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
static inline bool __fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code,
const exit_handler_fn *handlers)
{
/*
* Save PSTATE early so that we can evaluate the vcpu mode
* early on.
*/
synchronize_vcpu_pstate(vcpu, exit_code);
/*
* Check whether we want to repaint the state one way or
* another.
*/
early_exit_filter(vcpu, exit_code);
if (ARM_EXCEPTION_CODE(*exit_code) != ARM_EXCEPTION_IRQ)
vcpu->arch.fault.esr_el2 = read_sysreg_el2(SYS_ESR);
@ -768,7 +750,7 @@ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
goto exit;
/* Check if there's an exit handler and allow it to handle the exit. */
if (kvm_hyp_handle_exit(vcpu, exit_code))
if (kvm_hyp_handle_exit(vcpu, exit_code, handlers))
goto guest;
exit:
/* Return to the host kernel and handle the exit */

28
arch/arm64/kvm/hyp/nvhe/switch.c
View file

@ -250,19 +250,21 @@ static const exit_handler_fn *kvm_get_exit_handler_array(struct kvm_vcpu *vcpu)
return hyp_exit_handlers;
}
/*
* Some guests (e.g., protected VMs) are not be allowed to run in AArch32.
* The ARMv8 architecture does not give the hypervisor a mechanism to prevent a
* guest from dropping to AArch32 EL0 if implemented by the CPU. If the
* hypervisor spots a guest in such a state ensure it is handled, and don't
* trust the host to spot or fix it. The check below is based on the one in
* kvm_arch_vcpu_ioctl_run().
*
* Returns false if the guest ran in AArch32 when it shouldn't have, and
* thus should exit to the host, or true if a the guest run loop can continue.
*/
static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code)
static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
{
const exit_handler_fn *handlers = kvm_get_exit_handler_array(vcpu);
synchronize_vcpu_pstate(vcpu, exit_code);
/*
* Some guests (e.g., protected VMs) are not be allowed to run in
* AArch32. The ARMv8 architecture does not give the hypervisor a
* mechanism to prevent a guest from dropping to AArch32 EL0 if
* implemented by the CPU. If the hypervisor spots a guest in such a
* state ensure it is handled, and don't trust the host to spot or fix
* it. The check below is based on the one in
* kvm_arch_vcpu_ioctl_run().
*/
if (unlikely(vcpu_is_protected(vcpu) && vcpu_mode_is_32bit(vcpu))) {
/*
* As we have caught the guest red-handed, decide that it isn't
@ -275,6 +277,8 @@ static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code)
*exit_code &= BIT(ARM_EXIT_WITH_SERROR_BIT);
*exit_code |= ARM_EXCEPTION_IL;
}
return __fixup_guest_exit(vcpu, exit_code, handlers);
}
/* Switch to the guest for legacy non-VHE systems */

9
arch/arm64/kvm/hyp/vhe/switch.c
View file

@ -540,13 +540,10 @@ static const exit_handler_fn hyp_exit_handlers[] = {
[ESR_ELx_EC_MOPS] = kvm_hyp_handle_mops,
};
static const exit_handler_fn *kvm_get_exit_handler_array(struct kvm_vcpu *vcpu)
static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
{
return hyp_exit_handlers;
}
synchronize_vcpu_pstate(vcpu, exit_code);
static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code)
{
/*
* If we were in HYP context on entry, adjust the PSTATE view
* so that the usual helpers work correctly.
@ -566,6 +563,8 @@ static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code)
*vcpu_cpsr(vcpu) &= ~(PSR_MODE_MASK | PSR_MODE32_BIT);
*vcpu_cpsr(vcpu) |= mode;
}
return __fixup_guest_exit(vcpu, exit_code, hyp_exit_handlers);
}
/* Switch to the guest for VHE systems running in EL2 */