Hi Mirela, On 20/04/18 13:25, Mirela Simonovic wrote:
In existing code the paging for non-boot CPUs is setup only on boot. The setup is triggered from start_xen() after all CPUs are brought online. In other words, the initialization of VTCR_EL2 register is done out of the cpu_up/start_secondary() control flow. However, the cpu_up flow is also used to hotplug non-boot CPUs on resume from suspend to RAM state, in which case the virtual paging will not be configured. With this patch the setting of paging is triggered from start_secondary() function if the current system state is not boot. This way, the paging for secondary CPUs will be setup in non-boot scenarios as well, while the setup in boot scenario remains unchanged. It is assumed here that after the system completed the boot, CPUs that execute start_secondary() were booted as well when the Xen itself was booted. According to this assumption non-boot CPUs will always be compliant with the VTCR_EL2 value that was selected by Xen on boot. Currently, these in no mechanism to trigger hotplugging of a CPU. This will be added with the suspend to RAM support for ARM, where the hotplug of non-boot CPUs will be triggered via enable_nonboot_cpus() call.Signed-off-by: Mirela Simonovic <mirela.simono...@aggios.com> --- CC: Stefano Stabellini <sstabell...@kernel.org> CC: Julien Grall <julien.gr...@arm.com> --- Changes in v2: -Fix commit message -Save configured VTCR_EL2 value into static variable that will be used by non-boot CPUs on hotplug -Add setup_virt_paging_secondary() and invoke it from start_secondary() if that CPU has to setup virtual paging (if the system state is not boot) --- xen/arch/arm/p2m.c | 13 ++++++++++++- xen/arch/arm/smpboot.c | 3 +++ xen/include/asm-arm/p2m.h | 3 +++ 3 files changed, 18 insertions(+), 1 deletion(-) diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c index d43c3aa896..9bb62c13cd 100644 --- a/xen/arch/arm/p2m.c +++ b/xen/arch/arm/p2m.c @@ -1451,13 +1451,21 @@ err: return page; }-static void __init setup_virt_paging_one(void *data)+static void setup_virt_paging_one(void *data) { unsigned long val = (unsigned long)data; WRITE_SYSREG32(val, VTCR_EL2); isb(); }+/* VTCR value to be configured by all CPUs. Set only once by the boot CPU */+static unsigned long __read_mostly vtcr_value;
VTCR is a register, so the type should be represented in term of bits (i.e uint*_t).
+
+void setup_virt_paging_secondary(void)
+{
+ setup_virt_paging_one((void *)vtcr_value);
That's fairly ugly. Is there any way to rework the interface? For instance, because you have a static variable which contain the VTCR, you could just use the variable in setup_virt_paging one.
I think this code needs some documentation. So people understand why you only call setup_virt_paging_secondary() after boot. But is there any reason to not use a notifier (see notify_cpu_starting)? This would avoid yet another export.+} + void __init setup_virt_paging(void) { /* Setup Stage 2 address translation */ @@ -1540,6 +1548,9 @@ void __init setup_virt_paging(void) BUG_ON( P2M_ROOT_LEVEL == 0 && P2M_ROOT_ORDER > 0 ); setup_virt_paging_one((void *)val); smp_call_function(setup_virt_paging_one, (void *)val, 1); + + /* Save configured value (to be used later for secondary CPUs hotplug) */ + vtcr_value = val; }/*diff --git a/xen/arch/arm/smpboot.c b/xen/arch/arm/smpboot.c index 38b665a6d2..abc642804f 100644 --- a/xen/arch/arm/smpboot.c +++ b/xen/arch/arm/smpboot.c @@ -358,6 +358,9 @@ void start_secondary(unsigned long boot_phys_offset, local_irq_enable(); local_abort_enable();+ if ( system_state != SYS_STATE_boot )+ setup_virt_paging_secondary();
+ check_local_cpu_errata();printk(XENLOG_DEBUG "CPU %u booted.\n", smp_processor_id());diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h index 8823707c17..85b66a1196 100644 --- a/xen/include/asm-arm/p2m.h +++ b/xen/include/asm-arm/p2m.h @@ -153,6 +153,9 @@ void p2m_altp2m_check(struct vcpu *v, uint16_t idx) /* Second stage paging setup, to be called on all CPUs */ void setup_virt_paging(void);+/* To be called by secondary CPU on hotplug */+void setup_virt_paging_secondary(void); + /* Init the datastructures for later use by the p2m code */ int p2m_init(struct domain *d);
Cheers, -- Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
