diff options
| author | Marc Zyngier <maz@kernel.org> | 2022-09-19 10:59:29 +0100 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2022-09-19 10:59:29 +0100 |
| commit | bb0cca240a16dd9721c6ee1d55865465a3fb7211 (patch) | |
| tree | 0edffa391ceab05e4dfdff18c40d4213ff566d23 /arch/arm64/kvm/debug.c | |
| parent | b04b3315021a524d5eecdb6de0d24cf7371d4abf (diff) | |
| parent | b18e4d4aebdddd05810ceb2f73d7f72afcd11b41 (diff) | |
Merge branch kvm-arm64/single-step-async-exception into kvmarm-master/next
* kvm-arm64/single-step-async-exception:
: .
: Single-step fixes from Reiji Watanabe:
:
: "This series fixes two bugs of single-step execution enabled by
: userspace, and add a test case for KVM_GUESTDBG_SINGLESTEP to
: the debug-exception test to verify the single-step behavior."
: .
KVM: arm64: selftests: Add a test case for KVM_GUESTDBG_SINGLESTEP
KVM: arm64: selftests: Refactor debug-exceptions to make it amenable to new test cases
KVM: arm64: Clear PSTATE.SS when the Software Step state was Active-pending
KVM: arm64: Preserve PSTATE.SS for the guest while single-step is enabled
Signed-off-by: Marc Zyngier <maz@kernel.org>
Diffstat (limited to 'arch/arm64/kvm/debug.c')
| -rw-r--r-- | arch/arm64/kvm/debug.c | 34 |
1 files changed, 33 insertions, 1 deletions
diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c index 3f7563d768e2..fccf9ec01813 100644 --- a/arch/arm64/kvm/debug.c +++ b/arch/arm64/kvm/debug.c @@ -32,6 +32,10 @@ static DEFINE_PER_CPU(u64, mdcr_el2); * * Guest access to MDSCR_EL1 is trapped by the hypervisor and handled * after we have restored the preserved value to the main context. + * + * When single-step is enabled by userspace, we tweak PSTATE.SS on every + * guest entry. Preserve PSTATE.SS so we can restore the original value + * for the vcpu after the single-step is disabled. */ static void save_guest_debug_regs(struct kvm_vcpu *vcpu) { @@ -41,6 +45,9 @@ static void save_guest_debug_regs(struct kvm_vcpu *vcpu) trace_kvm_arm_set_dreg32("Saved MDSCR_EL1", vcpu->arch.guest_debug_preserved.mdscr_el1); + + vcpu->arch.guest_debug_preserved.pstate_ss = + (*vcpu_cpsr(vcpu) & DBG_SPSR_SS); } static void restore_guest_debug_regs(struct kvm_vcpu *vcpu) @@ -51,6 +58,11 @@ static void restore_guest_debug_regs(struct kvm_vcpu *vcpu) trace_kvm_arm_set_dreg32("Restored MDSCR_EL1", vcpu_read_sys_reg(vcpu, MDSCR_EL1)); + + if (vcpu->arch.guest_debug_preserved.pstate_ss) + *vcpu_cpsr(vcpu) |= DBG_SPSR_SS; + else + *vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS; } /** @@ -188,7 +200,18 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) * debugging the system. */ if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { - *vcpu_cpsr(vcpu) |= DBG_SPSR_SS; + /* + * If the software step state at the last guest exit + * was Active-pending, we don't set DBG_SPSR_SS so + * that the state is maintained (to not run another + * single-step until the pending Software Step + * exception is taken). + */ + if (!vcpu_get_flag(vcpu, DBG_SS_ACTIVE_PENDING)) + *vcpu_cpsr(vcpu) |= DBG_SPSR_SS; + else + *vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS; + mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1); mdscr |= DBG_MDSCR_SS; vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1); @@ -262,6 +285,15 @@ void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) * Restore the guest's debug registers if we were using them. */ if (vcpu->guest_debug || kvm_vcpu_os_lock_enabled(vcpu)) { + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { + if (!(*vcpu_cpsr(vcpu) & DBG_SPSR_SS)) + /* + * Mark the vcpu as ACTIVE_PENDING + * until Software Step exception is taken. + */ + vcpu_set_flag(vcpu, DBG_SS_ACTIVE_PENDING); + } + restore_guest_debug_regs(vcpu); /* |