Hi Julien, On 21/01/2019 15:33, Julien Thierry wrote: > When using VHE, the host needs to clear HCR_EL2.TGE bit in order > to interract with guest TLBs, switching from EL2&0 translation regime
(interact) > to EL1&0. > > However, some non-maskable asynchronous event could happen while TGE is > cleared like SDEI. Because of this address translation operations > relying on EL2&0 translation regime could fail (tlb invalidation, > userspace access, ...). > > Fix this by properly setting HCR_EL2.TGE when entering NMI context and > clear it if necessary when returning to the interrupted context. Yes please. This would not have been fun to debug! Reviewed-by: James Morse <[email protected]> I was looking for why we need core code to do this, instead of updating the arch's call sites. Your 'irqdesc: Add domain handlers for NMIs' patch (pointed to from the cover letter) is the reason: core-code calls nmi_enter()/nmi_exit() itself. Thanks, James > diff --git a/arch/arm64/include/asm/hardirq.h > b/arch/arm64/include/asm/hardirq.h > index 1473fc2..94b7481 100644 > --- a/arch/arm64/include/asm/hardirq.h > +++ b/arch/arm64/include/asm/hardirq.h > @@ -19,6 +19,7 @@ > #include <linux/cache.h> > #include <linux/threads.h> > #include <asm/irq.h> > +#include <asm/kvm_arm.h> percpu.h? sysreg.h? barrier.h? > @@ -37,6 +38,33 @@ > > #define __ARCH_IRQ_EXIT_IRQS_DISABLED 1 > > +struct nmi_ctx { > + u64 hcr; > +}; > + > +DECLARE_PER_CPU(struct nmi_ctx, nmi_contexts); > + > +#define arch_nmi_enter() > \ > + do { > \ > + if (is_kernel_in_hyp_mode()) { > \ > + struct nmi_ctx *nmi_ctx = this_cpu_ptr(&nmi_contexts); > \ > + nmi_ctx->hcr = read_sysreg(hcr_el2); > \ > + if (!(nmi_ctx->hcr & HCR_TGE)) { > \ > + write_sysreg(nmi_ctx->hcr | HCR_TGE, hcr_el2); > \ > + isb(); > \ > + } > \ > + } > \ > + } while (0) > + > +#define arch_nmi_exit() > \ > + do { > \ > + if (is_kernel_in_hyp_mode()) { > \ > + struct nmi_ctx *nmi_ctx = this_cpu_ptr(&nmi_contexts); > \ > + if (!(nmi_ctx->hcr & HCR_TGE)) > \ > + write_sysreg(nmi_ctx->hcr, hcr_el2); > \ > + } > \ > + } while (0) > + > static inline void ack_bad_irq(unsigned int irq) > { > extern unsigned long irq_err_count; > diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h > index 0fbbcdf..da0af63 100644 > --- a/include/linux/hardirq.h > +++ b/include/linux/hardirq.h > @@ -60,8 +60,14 @@ static inline void rcu_nmi_exit(void) > */ > extern void irq_exit(void); > > +#ifndef arch_nmi_enter > +#define arch_nmi_enter() do { } while (0) > +#define arch_nmi_exit() do { } while (0) > +#endif > + > #define nmi_enter() \ > do { \ > + arch_nmi_enter(); \ > printk_nmi_enter(); \ > lockdep_off(); \ > ftrace_nmi_enter(); \ > @@ -80,6 +86,7 @@ static inline void rcu_nmi_exit(void) > ftrace_nmi_exit(); \ > lockdep_on(); \ > printk_nmi_exit(); \ > + arch_nmi_exit(); \ > } while (0) > > #endif /* LINUX_HARDIRQ_H */ >
