From mboxrd@z Thu Jan 1 00:00:00 1970 From: marc.zyngier@arm.com (Marc Zyngier) Date: Thu, 20 Feb 2014 15:26:54 +0000 Subject: [PATCH] arm/arm64: KVM: detect CPU reset on CPU_PM_EXIT Message-ID: <1392910014-15495-1-git-send-email-marc.zyngier@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Commit 1fcf7ce0c602 (arm: kvm: implement CPU PM notifier) added support for CPU power-management, using a cpu_nofigier to re-init KVM on a CPU that entered CPU idle. The code assumed that a CPU entering idle would actually be powered off, loosing its state entierely, and would then need to be reinitialized. It turns out that this is not always the case, and some HW performs CPU PM without actually killing the core. In this case, we try to reinitialize KVM while it still live. It ends up badly, as reported by Andre Przywara (using a Calxeda Midway): [ 3.663897] Kernel panic - not syncing: unexpected prefetch abort in Hyp mode at: 0x685760 [ 3.663897] unexpected data abort in Hyp mode at: 0xc067d150 [ 3.663897] unexpected HVC/SVC trap in Hyp mode at: 0xc0901dd0 The trick here is to detect if we've been through a full re-init or not by looking at HVBAR (VBAR_EL2 on arm64). This involves implementing the backend for __hyp_get_vectors in the main KVM HYP code (rather small), and checking the return value against the default one when the CPU notifier is called on CPU_PM_EXIT. Reported-by: Andre Przywara Cc: Lorenzo Pieralisi Cc: Rob Herring Signed-off-by: Marc Zyngier --- arch/arm/kvm/arm.c | 3 ++- arch/arm/kvm/interrupts.S | 7 ++++++- arch/arm64/kvm/hyp.S | 9 +++++++-- 3 files changed, 15 insertions(+), 4 deletions(-) diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 1d8248e..bd18bb8 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -878,7 +878,8 @@ static int hyp_init_cpu_pm_notifier(struct notifier_block *self, unsigned long cmd, void *v) { - if (cmd == CPU_PM_EXIT) { + if (cmd == CPU_PM_EXIT && + __hyp_get_vectors() == hyp_default_vectors) { cpu_init_hyp_mode(NULL); return NOTIFY_OK; } diff --git a/arch/arm/kvm/interrupts.S b/arch/arm/kvm/interrupts.S index ddc1553..9b0ff68 100644 --- a/arch/arm/kvm/interrupts.S +++ b/arch/arm/kvm/interrupts.S @@ -363,6 +363,11 @@ hyp_hvc: host_switch_to_hyp: pop {r0, r1, r2} + /* Check for __hyp_get_vectors */ + cmp r0, #-1 + mrceq p15, 4, r0, c12, c0, 0 @ get HVBAR + beq 1f + push {lr} mrs lr, SPSR push {lr} @@ -378,7 +383,7 @@ THUMB( orr lr, #1) pop {lr} msr SPSR_csxf, lr pop {lr} - eret +1: eret guest_trap: load_vcpu @ Load VCPU pointer to r0 diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S index 3b47c36..f1cbabe 100644 --- a/arch/arm64/kvm/hyp.S +++ b/arch/arm64/kvm/hyp.S @@ -737,7 +737,12 @@ el1_sync: // Guest trapped into EL2 pop x2, x3 pop x0, x1 - push lr, xzr + /* Check for __hyp_get_vectors */ + cbnz x0, 1f + mrs x0, vbar_el2 + b 2f + +1: push lr, xzr /* * Compute the function address in EL2, and shuffle the parameters. @@ -750,7 +755,7 @@ el1_sync: // Guest trapped into EL2 blr lr pop lr, xzr - eret +2: eret el1_trap: /* -- 1.8.3.4