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Subject[PATCH v9 01/26] arm64: Fix HCR.TGE status for NMI contexts
Date
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
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>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
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
---
arch/arm64/include/asm/hardirq.h | 28 ++++++++++++++++++++++++++++
arch/arm64/kernel/irq.c | 3 +++
include/linux/hardirq.h | 7 +++++++
3 files changed, 38 insertions(+)

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>

#define NR_IPI 7

@@ -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/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c
index 780a12f..92fa817 100644
--- a/arch/arm64/kernel/irq.c
+++ b/arch/arm64/kernel/irq.c
@@ -33,6 +33,9 @@

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)
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 */
--
1.9.1
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