From 7839c672e58bf62da8f2f0197fefb442c02ba1dd Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Thu, 7 Dec 2017 11:45:45 +0000 Subject: KVM: arm/arm64: Fix HYP unmapping going off limits When we unmap the HYP memory, we try to be clever and unmap one PGD at a time. If we start with a non-PGD aligned address and try to unmap a whole PGD, things go horribly wrong in unmap_hyp_range (addr and end can never match, and it all goes really badly as we keep incrementing pgd and parse random memory as page tables...). The obvious fix is to let unmap_hyp_range do what it does best, which is to iterate over a range. The size of the linear mapping, which begins at PAGE_OFFSET, can be easily calculated by subtracting PAGE_OFFSET form high_memory, because high_memory is defined as the linear map address of the last byte of DRAM, plus one. The size of the vmalloc region is given trivially by VMALLOC_END - VMALLOC_START. Cc: stable@vger.kernel.org Reported-by: Andre Przywara Tested-by: Andre Przywara Reviewed-by: Christoffer Dall Signed-off-by: Marc Zyngier Signed-off-by: Christoffer Dall --- virt/kvm/arm/mmu.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) (limited to 'virt') diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c index b36945d49986..b4b69c2d1012 100644 --- a/virt/kvm/arm/mmu.c +++ b/virt/kvm/arm/mmu.c @@ -509,8 +509,6 @@ static void unmap_hyp_range(pgd_t *pgdp, phys_addr_t start, u64 size) */ void free_hyp_pgds(void) { - unsigned long addr; - mutex_lock(&kvm_hyp_pgd_mutex); if (boot_hyp_pgd) { @@ -521,10 +519,10 @@ void free_hyp_pgds(void) if (hyp_pgd) { unmap_hyp_range(hyp_pgd, hyp_idmap_start, PAGE_SIZE); - for (addr = PAGE_OFFSET; virt_addr_valid(addr); addr += PGDIR_SIZE) - unmap_hyp_range(hyp_pgd, kern_hyp_va(addr), PGDIR_SIZE); - for (addr = VMALLOC_START; is_vmalloc_addr((void*)addr); addr += PGDIR_SIZE) - unmap_hyp_range(hyp_pgd, kern_hyp_va(addr), PGDIR_SIZE); + unmap_hyp_range(hyp_pgd, kern_hyp_va(PAGE_OFFSET), + (uintptr_t)high_memory - PAGE_OFFSET); + unmap_hyp_range(hyp_pgd, kern_hyp_va(VMALLOC_START), + VMALLOC_END - VMALLOC_START); free_pages((unsigned long)hyp_pgd, hyp_pgd_order); hyp_pgd = NULL; -- cgit v1.2.3-59-g8ed1b From f384dcfe4d918c1d80477d290c22ce0093823771 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Thu, 7 Dec 2017 11:46:15 +0000 Subject: KVM: arm/arm64: timer: Don't set irq as forwarded if no usable GIC If we don't have a usable GIC, do not try to set the vcpu affinity as this is guaranteed to fail. Reported-by: Andre Przywara Reviewed-by: Andre Przywara Tested-by: Andre Przywara Reviewed-by: Christoffer Dall Signed-off-by: Marc Zyngier Signed-off-by: Christoffer Dall --- include/kvm/arm_arch_timer.h | 2 +- virt/kvm/arm/arch_timer.c | 13 ++++++++----- virt/kvm/arm/arm.c | 2 +- 3 files changed, 10 insertions(+), 7 deletions(-) (limited to 'virt') diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h index 6e45608b2399..9da6ce22803f 100644 --- a/include/kvm/arm_arch_timer.h +++ b/include/kvm/arm_arch_timer.h @@ -62,7 +62,7 @@ struct arch_timer_cpu { bool enabled; }; -int kvm_timer_hyp_init(void); +int kvm_timer_hyp_init(bool); int kvm_timer_enable(struct kvm_vcpu *vcpu); int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu); void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu); diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c index f9555b1e7f15..aa9adfafe12b 100644 --- a/virt/kvm/arm/arch_timer.c +++ b/virt/kvm/arm/arch_timer.c @@ -720,7 +720,7 @@ static int kvm_timer_dying_cpu(unsigned int cpu) return 0; } -int kvm_timer_hyp_init(void) +int kvm_timer_hyp_init(bool has_gic) { struct arch_timer_kvm_info *info; int err; @@ -756,10 +756,13 @@ int kvm_timer_hyp_init(void) return err; } - err = irq_set_vcpu_affinity(host_vtimer_irq, kvm_get_running_vcpus()); - if (err) { - kvm_err("kvm_arch_timer: error setting vcpu affinity\n"); - goto out_free_irq; + if (has_gic) { + err = irq_set_vcpu_affinity(host_vtimer_irq, + kvm_get_running_vcpus()); + if (err) { + kvm_err("kvm_arch_timer: error setting vcpu affinity\n"); + goto out_free_irq; + } } kvm_info("virtual timer IRQ%d\n", host_vtimer_irq); diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index 6b60c98a6e22..2e43f9d42bd5 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -1326,7 +1326,7 @@ static int init_subsystems(void) /* * Init HYP architected timer support */ - err = kvm_timer_hyp_init(); + err = kvm_timer_hyp_init(vgic_present); if (err) goto out; -- cgit v1.2.3-59-g8ed1b From 36e5cfd410ad6060b527e51d1b4bc174a8068cfd Mon Sep 17 00:00:00 2001 From: Christoffer Dall Date: Thu, 14 Dec 2017 19:54:50 +0100 Subject: KVM: arm/arm64: Properly handle arch-timer IRQs after vtimer_save_state The recent timer rework was assuming that once the timer was disabled, we should no longer see any interrupts from the timer. This assumption turns out to not be true, and instead we have to handle the case when the timer ISR runs even after the timer has been disabled. This requires a couple of changes: First, we should never overwrite the cached guest state of the timer control register when the ISR runs, because KVM may have disabled its timers when doing vcpu_put(), even though the guest still had the timer enabled. Second, we shouldn't assume that the timer is actually firing just because we see an interrupt, but we should check the actual state of the timer in the timer control register to understand if the hardware timer is really firing or not. We also add an ISB to vtimer_save_state() to ensure the timer is actually disabled once we enable interrupts, which should clarify the intention of the implementation, and reduce the risk of unwanted interrupts. Fixes: b103cc3f10c0 ("KVM: arm/arm64: Avoid timer save/restore in vcpu entry/exit") Reported-by: Marc Zyngier Reported-by: Jia He Reviewed-by: Marc Zyngier Tested-by: Marc Zyngier Signed-off-by: Christoffer Dall --- virt/kvm/arm/arch_timer.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-) (limited to 'virt') diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c index aa9adfafe12b..14c018f990a7 100644 --- a/virt/kvm/arm/arch_timer.c +++ b/virt/kvm/arm/arch_timer.c @@ -92,16 +92,23 @@ static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id) { struct kvm_vcpu *vcpu = *(struct kvm_vcpu **)dev_id; struct arch_timer_context *vtimer; + u32 cnt_ctl; - if (!vcpu) { - pr_warn_once("Spurious arch timer IRQ on non-VCPU thread\n"); - return IRQ_NONE; - } - vtimer = vcpu_vtimer(vcpu); + /* + * We may see a timer interrupt after vcpu_put() has been called which + * sets the CPU's vcpu pointer to NULL, because even though the timer + * has been disabled in vtimer_save_state(), the hardware interrupt + * signal may not have been retired from the interrupt controller yet. + */ + if (!vcpu) + return IRQ_HANDLED; + vtimer = vcpu_vtimer(vcpu); if (!vtimer->irq.level) { - vtimer->cnt_ctl = read_sysreg_el0(cntv_ctl); - if (kvm_timer_irq_can_fire(vtimer)) + cnt_ctl = read_sysreg_el0(cntv_ctl); + cnt_ctl &= ARCH_TIMER_CTRL_ENABLE | ARCH_TIMER_CTRL_IT_STAT | + ARCH_TIMER_CTRL_IT_MASK; + if (cnt_ctl == (ARCH_TIMER_CTRL_ENABLE | ARCH_TIMER_CTRL_IT_STAT)) kvm_timer_update_irq(vcpu, true, vtimer); } @@ -355,6 +362,7 @@ static void vtimer_save_state(struct kvm_vcpu *vcpu) /* Disable the virtual timer */ write_sysreg_el0(0, cntv_ctl); + isb(); vtimer->loaded = false; out: -- cgit v1.2.3-59-g8ed1b From 0eb7c33cadf6b2f1a94e58ded8b0eb89b4eba382 Mon Sep 17 00:00:00 2001 From: Christoffer Dall Date: Fri, 15 Dec 2017 00:30:12 +0100 Subject: KVM: arm/arm64: Fix timer enable flow When enabling the timer on the first run, we fail to ever restore the state and mark it as loaded. That means, that in the initial entry to the VCPU ioctl, unless we exit to userspace for some reason such as a pending signal, if the guest programs a timer and blocks, we will wait forever, because we never read back the hardware state (the loaded flag is not set), and so we think the timer is disabled, and we never schedule a background soft timer. The end result? The VCPU blocks forever, and the only solution is to kill the thread. Fixes: 4a2c4da1250d ("arm/arm64: KVM: Load the timer state when enabling the timer") Reported-by: Marc Zyngier Reviewed-by: Marc Zyngier Tested-by: Marc Zyngier Signed-off-by: Christoffer Dall --- virt/kvm/arm/arch_timer.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'virt') diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c index 14c018f990a7..cc29a8148328 100644 --- a/virt/kvm/arm/arch_timer.c +++ b/virt/kvm/arm/arch_timer.c @@ -846,10 +846,7 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu) no_vgic: preempt_disable(); timer->enabled = 1; - if (!irqchip_in_kernel(vcpu->kvm)) - kvm_timer_vcpu_load_user(vcpu); - else - kvm_timer_vcpu_load_vgic(vcpu); + kvm_timer_vcpu_load(vcpu); preempt_enable(); return 0; -- cgit v1.2.3-59-g8ed1b