From: Andrew Murray andrew.murray@arm.com

mainline inclusion from mainline-v5.6 commit 4942dc6638b07b5326b6d2faa142635c559e7cd5 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5QR6C CVE: NA

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On VHE systems arch.mdcr_el2 is written to mdcr_el2 at vcpu_load time to set options for self-hosted debug and the performance monitors extension.

Unfortunately the value of arch.mdcr_el2 is not calculated until kvm_arm_setup_debug() in the run loop after the vcpu has been loaded. This means that the initial brief iterations of the run loop use a zero value of mdcr_el2 - until the vcpu is preempted. This also results in a delay between changes to vcpu->guest_debug taking effect.

Fix this by writing to mdcr_el2 in kvm_arm_setup_debug() on VHE systems when a change to arch.mdcr_el2 has been detected.

Fixes: d5a21bcc2995 ("KVM: arm64: Move common VHE/non-VHE trap config in separate functions") Cc: stable@vger.kernel.org # 4.17.x- Suggested-by: James Morse james.morse@arm.com Acked-by: Will Deacon will@kernel.org Reviewed-by: Marc Zyngier maz@kernel.org Signed-off-by: Andrew Murray andrew.murray@arm.com Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Zengruan Ye yezengruan@huawei.com Reviewed-by: Keqian Zhu zhukeqian1@huawei.com Signed-off-by: Laibin Qiu qiulaibin@huawei.com --- arch/arm64/kvm/debug.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c index 00d422336a45..4e722d73a3c3 100644 --- a/arch/arm64/kvm/debug.c +++ b/arch/arm64/kvm/debug.c @@ -112,7 +112,7 @@ void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu) void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) { bool trap_debug = !(vcpu->arch.flags & KVM_ARM64_DEBUG_DIRTY); - unsigned long mdscr; + unsigned long mdscr, orig_mdcr_el2 = vcpu->arch.mdcr_el2;

trace_kvm_arm_setup_debug(vcpu, vcpu->guest_debug);

@@ -208,6 +208,10 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) if (vcpu_read_sys_reg(vcpu, MDSCR_EL1) & (DBG_MDSCR_KDE | DBG_MDSCR_MDE)) vcpu->arch.flags |= KVM_ARM64_DEBUG_DIRTY;

+ /* Write mdcr_el2 changes since vcpu_load on VHE systems */ + if (has_vhe() && orig_mdcr_el2 != vcpu->arch.mdcr_el2) + write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2); + trace_kvm_arm_set_dreg32("MDCR_EL2", vcpu->arch.mdcr_el2); trace_kvm_arm_set_dreg32("MDSCR_EL1", vcpu_read_sys_reg(vcpu, MDSCR_EL1)); }