arm64: Fix HCR.TGE status for NMI contexts

commit 5870970 upstream.

When using VHE, the host needs to clear HCR_EL2.TGE bit in order
to interact with guest TLBs, switching from EL2&0 translation regime
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.

Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Suggested-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: James Morse <james.morse@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: linux-arch@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/arm64/include/asm/hardirq.h

@@ -17,8 +17,12 @@
 #define __ASM_HARDIRQ_H
 
 #include <linux/cache.h>
+#include <linux/percpu.h>
 #include <linux/threads.h>
+#include <asm/barrier.h>
 #include <asm/irq.h>
+#include <asm/kvm_arm.h>
+#include <asm/sysreg.h>
 
 #define NR_IPI 7
 
@@ -37,6 +41,33 @@ u64 smp_irq_stat_cpu(unsigned int cpu);
 
 #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;

arch/arm64/kernel/irq.c

@@ -32,6 +32,9 @@
 
 unsigned long irq_err_count;
 
+/* Only access this in an NMI enter/exit */
+DEFINE_PER_CPU(struct nmi_ctx, nmi_contexts);
+
 DEFINE_PER_CPU(unsigned long *, irq_stack_ptr);
 
 int arch_show_interrupts(struct seq_file *p, int prec)

include/linux/hardirq.h

@@ -60,8 +60,14 @@ extern void irq_enter(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 @@ extern void irq_exit(void);
  ftrace_nmi_exit(); \
  lockdep_on(); \
  printk_nmi_exit(); \
+ arch_nmi_exit(); \
  } while (0)
 
 #endif /* LINUX_HARDIRQ_H */