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Message-ID: <20160201135928.GP1478@cbox>
Date: Mon, 1 Feb 2016 14:59:28 +0100
From: Christoffer Dall <christoffer.dall@...aro.org>
To: Marc Zyngier <marc.zyngier@....com>
Cc: Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
kvm@...r.kernel.org, kvmarm@...ts.cs.columbia.edu
Subject: Re: [PATCH v2 04/21] arm64: KVM: Skip HYP setup when already running
in HYP
On Mon, Jan 25, 2016 at 03:53:38PM +0000, Marc Zyngier wrote:
> With the kernel running at EL2, there is no point trying to
> configure page tables for HYP, as the kernel is already mapped.
>
> Take this opportunity to refactor the whole init a bit, allowing
> the various parts of the hypervisor bringup to be split across
> multiple functions.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@....com>
Reviewed-by: Christoffer Dall <christoffer.dall@...aro.org>
> ---
> arch/arm/kvm/arm.c | 151 +++++++++++++++++++++++++++++++++--------------------
> arch/arm/kvm/mmu.c | 7 +++
> 2 files changed, 100 insertions(+), 58 deletions(-)
>
> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
> index dda1959..66e2d04 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -1035,6 +1035,67 @@ static inline void hyp_cpu_pm_init(void)
> }
> #endif
>
> +static void teardown_common_resources(void)
> +{
> + free_percpu(kvm_host_cpu_state);
> +}
> +
> +static int init_common_resources(void)
> +{
> + kvm_host_cpu_state = alloc_percpu(kvm_cpu_context_t);
> + if (!kvm_host_cpu_state) {
> + kvm_err("Cannot allocate host CPU state\n");
> + return -ENOMEM;
> + }
> +
> + return 0;
> +}
> +
> +static int init_subsystems(void)
> +{
> + int err;
> +
> + /*
> + * Init HYP view of VGIC
> + */
> + err = kvm_vgic_hyp_init();
> + switch (err) {
> + case 0:
> + vgic_present = true;
> + break;
> + case -ENODEV:
> + case -ENXIO:
> + vgic_present = false;
> + break;
> + default:
> + return err;
> + }
> +
> + /*
> + * Init HYP architected timer support
> + */
> + err = kvm_timer_hyp_init();
> + if (err)
> + return err;
> +
> + kvm_perf_init();
> + kvm_coproc_table_init();
> +
> + return 0;
> +}
> +
> +static void teardown_hyp_mode(void)
> +{
> + int cpu;
> +
> + if (is_kernel_in_hyp_mode())
> + return;
> +
> + free_hyp_pgds();
> + for_each_possible_cpu(cpu)
> + free_page(per_cpu(kvm_arm_hyp_stack_page, cpu));
> +}
> +
> /**
> * Inits Hyp-mode on all online CPUs
> */
> @@ -1043,6 +1104,9 @@ static int init_hyp_mode(void)
> int cpu;
> int err = 0;
>
> + if (is_kernel_in_hyp_mode())
> + return 0;
> +
> /*
> * Allocate Hyp PGD and setup Hyp identity mapping
> */
> @@ -1065,7 +1129,7 @@ static int init_hyp_mode(void)
> stack_page = __get_free_page(GFP_KERNEL);
> if (!stack_page) {
> err = -ENOMEM;
> - goto out_free_stack_pages;
> + goto out_err;
> }
>
> per_cpu(kvm_arm_hyp_stack_page, cpu) = stack_page;
> @@ -1077,13 +1141,13 @@ static int init_hyp_mode(void)
> err = create_hyp_mappings(__kvm_hyp_code_start, __kvm_hyp_code_end);
> if (err) {
> kvm_err("Cannot map world-switch code\n");
> - goto out_free_mappings;
> + goto out_err;
> }
>
> err = create_hyp_mappings(__start_rodata, __end_rodata);
> if (err) {
> kvm_err("Cannot map rodata section\n");
> - goto out_free_mappings;
> + goto out_err;
> }
>
> /*
> @@ -1095,20 +1159,10 @@ static int init_hyp_mode(void)
>
> if (err) {
> kvm_err("Cannot map hyp stack\n");
> - goto out_free_mappings;
> + goto out_err;
> }
> }
>
> - /*
> - * Map the host CPU structures
> - */
> - kvm_host_cpu_state = alloc_percpu(kvm_cpu_context_t);
> - if (!kvm_host_cpu_state) {
> - err = -ENOMEM;
> - kvm_err("Cannot allocate host CPU state\n");
> - goto out_free_mappings;
> - }
> -
> for_each_possible_cpu(cpu) {
> kvm_cpu_context_t *cpu_ctxt;
>
> @@ -1117,7 +1171,7 @@ static int init_hyp_mode(void)
>
> if (err) {
> kvm_err("Cannot map host CPU state: %d\n", err);
> - goto out_free_context;
> + goto out_err;
> }
> }
>
> @@ -1126,34 +1180,22 @@ static int init_hyp_mode(void)
> */
> on_each_cpu(cpu_init_hyp_mode, NULL, 1);
>
> - /*
> - * Init HYP view of VGIC
> - */
> - err = kvm_vgic_hyp_init();
> - switch (err) {
> - case 0:
> - vgic_present = true;
> - break;
> - case -ENODEV:
> - case -ENXIO:
> - vgic_present = false;
> - break;
> - default:
> - goto out_free_context;
> - }
> -
> - /*
> - * Init HYP architected timer support
> - */
> - err = kvm_timer_hyp_init();
> - if (err)
> - goto out_free_context;
> -
> #ifndef CONFIG_HOTPLUG_CPU
> free_boot_hyp_pgd();
> #endif
>
> - kvm_perf_init();
> + cpu_notifier_register_begin();
> +
> + err = __register_cpu_notifier(&hyp_init_cpu_nb);
> +
> + cpu_notifier_register_done();
> +
> + if (err) {
> + kvm_err("Cannot register HYP init CPU notifier (%d)\n", err);
> + goto out_err;
> + }
> +
> + hyp_cpu_pm_init();
>
> /* set size of VMID supported by CPU */
> kvm_vmid_bits = kvm_get_vmid_bits();
> @@ -1162,14 +1204,9 @@ static int init_hyp_mode(void)
> kvm_info("Hyp mode initialized successfully\n");
>
> return 0;
> -out_free_context:
> - free_percpu(kvm_host_cpu_state);
> -out_free_mappings:
> - free_hyp_pgds();
> -out_free_stack_pages:
> - for_each_possible_cpu(cpu)
> - free_page(per_cpu(kvm_arm_hyp_stack_page, cpu));
> +
> out_err:
> + teardown_hyp_mode();
> kvm_err("error initializing Hyp mode: %d\n", err);
> return err;
> }
> @@ -1213,26 +1250,24 @@ int kvm_arch_init(void *opaque)
> }
> }
>
> - cpu_notifier_register_begin();
> + err = init_common_resources();
> + if (err)
> + return err;
>
> err = init_hyp_mode();
> if (err)
> goto out_err;
>
> - err = __register_cpu_notifier(&hyp_init_cpu_nb);
> - if (err) {
> - kvm_err("Cannot register HYP init CPU notifier (%d)\n", err);
> - goto out_err;
> - }
> -
> - cpu_notifier_register_done();
> -
> - hyp_cpu_pm_init();
> + err = init_subsystems();
> + if (err)
> + goto out_hyp;
>
> - kvm_coproc_table_init();
> return 0;
> +
> +out_hyp:
> + teardown_hyp_mode();
> out_err:
> - cpu_notifier_register_done();
> + teardown_common_resources();
> return err;
> }
>
> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> index aba61fd..920d0c3 100644
> --- a/arch/arm/kvm/mmu.c
> +++ b/arch/arm/kvm/mmu.c
> @@ -28,6 +28,7 @@
> #include <asm/kvm_mmio.h>
> #include <asm/kvm_asm.h>
> #include <asm/kvm_emulate.h>
> +#include <asm/virt.h>
>
> #include "trace.h"
>
> @@ -598,6 +599,9 @@ int create_hyp_mappings(void *from, void *to)
> unsigned long start = KERN_TO_HYP((unsigned long)from);
> unsigned long end = KERN_TO_HYP((unsigned long)to);
>
> + if (is_kernel_in_hyp_mode())
> + return 0;
> +
> start = start & PAGE_MASK;
> end = PAGE_ALIGN(end);
>
> @@ -630,6 +634,9 @@ int create_hyp_io_mappings(void *from, void *to, phys_addr_t phys_addr)
> unsigned long start = KERN_TO_HYP((unsigned long)from);
> unsigned long end = KERN_TO_HYP((unsigned long)to);
>
> + if (is_kernel_in_hyp_mode())
> + return 0;
> +
> /* Check for a valid kernel IO mapping */
> if (!is_vmalloc_addr(from) || !is_vmalloc_addr(to - 1))
> return -EINVAL;
> --
> 2.1.4
>
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