diff options
| author | Oliver Upton <oliver.upton@linux.dev> | 2024-12-19 14:41:08 -0800 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2024-12-20 09:01:25 +0000 |
| commit | beb470d96cec8dd8f4e05b2135c74d828f7b114b (patch) | |
| tree | e1dabfe9e953a03706295ce0d95426647f704539 /arch/arm64/kvm/debug.c | |
| parent | 803602b0d94168bd25f5ff6eafdfd9388a6dd2ec (diff) | |
KVM: arm64: Use debug_owner to track if debug regs need save/restore
Use the debug owner to determine if the debug regs are in use instead of
keeping around the DEBUG_DIRTY flag. Debug registers are now
saved/restored after the first trap, regardless of whether it was a read
or a write. This also shifts the point at which KVM becomes lazy to
vcpu_put() rather than the next exception taken from the guest.
Tested-by: James Clark <james.clark@linaro.org>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20241219224116.3941496-12-oliver.upton@linux.dev
Signed-off-by: Marc Zyngier <maz@kernel.org>
Diffstat (limited to 'arch/arm64/kvm/debug.c')
| -rw-r--r-- | arch/arm64/kvm/debug.c | 19 |
1 files changed, 3 insertions, 16 deletions
diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c index f39004c52d33..a4ae17c31fa8 100644 --- a/arch/arm64/kvm/debug.c +++ b/arch/arm64/kvm/debug.c @@ -86,15 +86,9 @@ static void kvm_arm_setup_mdcr_el2(struct kvm_vcpu *vcpu) vcpu->arch.mdcr_el2 |= MDCR_EL2_TDE; /* - * Trap debug register access when one of the following is true: - * - Userspace is using the hardware to debug the guest - * (KVM_GUESTDBG_USE_HW is set). - * - The guest is not using debug (DEBUG_DIRTY clear). - * - The guest has enabled the OS Lock (debug exceptions are blocked). + * Trap debug registers if the guest doesn't have ownership of them. */ - if ((vcpu->guest_debug & KVM_GUESTDBG_USE_HW) || - !vcpu_get_flag(vcpu, DEBUG_DIRTY) || - kvm_vcpu_os_lock_enabled(vcpu)) + if (!kvm_guest_owns_debug_regs(vcpu)) vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA; /* Write MDCR_EL2 directly if we're already at EL2 */ @@ -127,8 +121,7 @@ void kvm_arm_vcpu_init_debug(struct kvm_vcpu *vcpu) * debug related registers. * * Additionally, KVM only traps guest accesses to the debug registers if - * the guest is not actively using them (see the DEBUG_DIRTY - * flag on vcpu->arch.iflags). Since the guest must not interfere + * the guest is not actively using them. Since the guest must not interfere * with the hardware state when debugging the guest, we must ensure that * trapping is enabled whenever we are debugging the guest using the * debug registers. @@ -195,8 +188,6 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) mdscr |= DBG_MDSCR_MDE; vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1); - vcpu_set_flag(vcpu, DEBUG_DIRTY); - /* * The OS Lock blocks debug exceptions in all ELs when it is * enabled. If the guest has enabled the OS Lock, constrain its @@ -211,10 +202,6 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1); } } - - /* If KDE or MDE are set, perform a full save/restore cycle. */ - if (vcpu_read_sys_reg(vcpu, MDSCR_EL1) & (DBG_MDSCR_KDE | DBG_MDSCR_MDE)) - vcpu_set_flag(vcpu, DEBUG_DIRTY); } void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) |