Re: [PATCH V13 10/10] arm/arm64: KVM: add guest SEA support

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On 21/03/17 22:47, Tyler Baicar wrote:
> Currently external aborts are unsupported by the guest abort
> handling. Add handling for SEAs so that the host kernel reports
> SEAs which occur in the guest kernel.
> 
> Signed-off-by: Tyler Baicar <tbaicar@xxxxxxxxxxxxxx>
> ---
>  arch/arm/include/asm/kvm_arm.h       | 10 +++++++++
>  arch/arm/include/asm/system_misc.h   |  5 +++++
>  arch/arm/kvm/mmu.c                   | 41 ++++++++++++++++++++++++++++++------
>  arch/arm64/include/asm/kvm_arm.h     | 10 +++++++++
>  arch/arm64/include/asm/system_misc.h |  2 ++
>  arch/arm64/mm/fault.c                | 19 +++++++++++++++--
>  drivers/acpi/apei/ghes.c             | 13 ++++++------
>  include/acpi/ghes.h                  |  2 +-
>  8 files changed, 86 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/arm/include/asm/kvm_arm.h b/arch/arm/include/asm/kvm_arm.h
> index a3f0b3d..ebf020b 100644
> --- a/arch/arm/include/asm/kvm_arm.h
> +++ b/arch/arm/include/asm/kvm_arm.h
> @@ -187,6 +187,16 @@
>  #define FSC_FAULT	(0x04)
>  #define FSC_ACCESS	(0x08)
>  #define FSC_PERM	(0x0c)
> +#define FSC_SEA		(0x10)
> +#define FSC_SEA_TTW0	(0x14)
> +#define FSC_SEA_TTW1	(0x15)
> +#define FSC_SEA_TTW2	(0x16)
> +#define FSC_SEA_TTW3	(0x17)
> +#define FSC_SECC	(0x18)
> +#define FSC_SECC_TTW0	(0x1c)
> +#define FSC_SECC_TTW1	(0x1d)
> +#define FSC_SECC_TTW2	(0x1e)
> +#define FSC_SECC_TTW3	(0x1f)
>  
>  /* Hyp Prefetch Fault Address Register (HPFAR/HDFAR) */
>  #define HPFAR_MASK	(~0xf)
> diff --git a/arch/arm/include/asm/system_misc.h b/arch/arm/include/asm/system_misc.h
> index a3d61ad..ea45d94 100644
> --- a/arch/arm/include/asm/system_misc.h
> +++ b/arch/arm/include/asm/system_misc.h
> @@ -24,4 +24,9 @@
>  
>  #endif /* !__ASSEMBLY__ */
>  
> +static inline int handle_guest_sea(unsigned long addr, unsigned int esr)
> +{
> +	return -1;
> +}
> +

Shouldn't this be in the #ifndef __ASSEMBLY__ block? The assembler is
definitely going to barf on that...

>  #endif /* __ASM_ARM_SYSTEM_MISC_H */
> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> index 962616f..105b6ab 100644
> --- a/arch/arm/kvm/mmu.c
> +++ b/arch/arm/kvm/mmu.c
> @@ -29,6 +29,7 @@
>  #include <asm/kvm_asm.h>
>  #include <asm/kvm_emulate.h>
>  #include <asm/virt.h>
> +#include <asm/system_misc.h>
>  
>  #include "trace.h"
>  
> @@ -1406,6 +1407,24 @@ static void handle_access_fault(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
>  		kvm_set_pfn_accessed(pfn);
>  }
>  
> +static bool is_abort_synchronous(unsigned long fault_status) {
> +	switch (fault_status) {
> +	case FSC_SEA:
> +	case FSC_SEA_TTW0:
> +	case FSC_SEA_TTW1:
> +	case FSC_SEA_TTW2:
> +	case FSC_SEA_TTW3:
> +	case FSC_SECC:
> +	case FSC_SECC_TTW0:
> +	case FSC_SECC_TTW1:
> +	case FSC_SECC_TTW2:
> +	case FSC_SECC_TTW3:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
>  /**
>   * kvm_handle_guest_abort - handles all 2nd stage aborts
>   * @vcpu:	the VCPU pointer
> @@ -1426,23 +1445,31 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run)
>  	unsigned long hva;
>  	bool is_iabt, write_fault, writable;
>  	gfn_t gfn;
> -	int ret, idx;
> +	int ret, idx, sea_status = 1;
> +
> +	/* Check the stage-2 fault is trans. fault or write fault */
> +	fault_status = kvm_vcpu_trap_get_fault_type(vcpu);
> +
> +	fault_ipa = kvm_vcpu_get_fault_ipa(vcpu);
> +
> +	/* The host kernel will handle the synchronous external abort. There
> +	 * is no need to pass the error into the guest.
> +	 */
> +	if (is_abort_synchronous(fault_status))
> +		sea_status = handle_guest_sea((unsigned long)fault_ipa,
> +				    kvm_vcpu_get_hsr(vcpu));
>  
>  	is_iabt = kvm_vcpu_trap_is_iabt(vcpu);
> -	if (unlikely(!is_iabt && kvm_vcpu_dabt_isextabt(vcpu))) {
> +	if (unlikely(!is_iabt && kvm_vcpu_dabt_isextabt(vcpu)) && sea_status) {
>  		kvm_inject_vabt(vcpu);
>  		return 1;
>  	}
>  
> -	fault_ipa = kvm_vcpu_get_fault_ipa(vcpu);
> -
>  	trace_kvm_guest_fault(*vcpu_pc(vcpu), kvm_vcpu_get_hsr(vcpu),
>  			      kvm_vcpu_get_hfar(vcpu), fault_ipa);
>  
> -	/* Check the stage-2 fault is trans. fault or write fault */
> -	fault_status = kvm_vcpu_trap_get_fault_type(vcpu);
>  	if (fault_status != FSC_FAULT && fault_status != FSC_PERM &&
> -	    fault_status != FSC_ACCESS) {
> +	    fault_status != FSC_ACCESS && sea_status) {
>  		kvm_err("Unsupported FSC: EC=%#x xFSC=%#lx ESR_EL2=%#lx\n",
>  			kvm_vcpu_trap_get_class(vcpu),
>  			(unsigned long)kvm_vcpu_trap_get_fault(vcpu),
> diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
> index 6e99978..61d694c 100644
> --- a/arch/arm64/include/asm/kvm_arm.h
> +++ b/arch/arm64/include/asm/kvm_arm.h
> @@ -204,6 +204,16 @@
>  #define FSC_FAULT	ESR_ELx_FSC_FAULT
>  #define FSC_ACCESS	ESR_ELx_FSC_ACCESS
>  #define FSC_PERM	ESR_ELx_FSC_PERM
> +#define FSC_SEA		ESR_ELx_FSC_EXTABT
> +#define FSC_SEA_TTW0	(0x14)
> +#define FSC_SEA_TTW1	(0x15)
> +#define FSC_SEA_TTW2	(0x16)
> +#define FSC_SEA_TTW3	(0x17)
> +#define FSC_SECC	(0x18)
> +#define FSC_SECC_TTW0	(0x1c)
> +#define FSC_SECC_TTW1	(0x1d)
> +#define FSC_SECC_TTW2	(0x1e)
> +#define FSC_SECC_TTW3	(0x1f)
>  
>  /* Hyp Prefetch Fault Address Register (HPFAR/HDFAR) */
>  #define HPFAR_MASK	(~UL(0xf))
> diff --git a/arch/arm64/include/asm/system_misc.h b/arch/arm64/include/asm/system_misc.h
> index bc81243..5b2cecd 100644
> --- a/arch/arm64/include/asm/system_misc.h
> +++ b/arch/arm64/include/asm/system_misc.h
> @@ -58,4 +58,6 @@ void hook_debug_fault_code(int nr, int (*fn)(unsigned long, unsigned int,
>  
>  #endif	/* __ASSEMBLY__ */
>  
> +int handle_guest_sea(unsigned long addr, unsigned int esr);

Same remark here.

> +
>  #endif	/* __ASM_SYSTEM_MISC_H */
> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> index f7372ce..ee96307 100644
> --- a/arch/arm64/mm/fault.c
> +++ b/arch/arm64/mm/fault.c
> @@ -497,6 +497,7 @@ static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
>  static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
>  {
>  	struct siginfo info;
> +	int ret = 0;
>  
>  	pr_err("Synchronous External Abort: %s (0x%08x) at 0x%016lx\n",
>  		 fault_name(esr), esr, addr);
> @@ -508,7 +509,7 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
>  	 */
>  	if (IS_ENABLED(CONFIG_ACPI_APEI_SEA)) {
>  		nmi_enter();
> -		ghes_notify_sea();
> +		ret = ghes_notify_sea();
>  		nmi_exit();
>  	}
>  
> @@ -521,7 +522,7 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
>  		info.si_addr  = (void __user *)addr;
>  	arm64_notify_die("", regs, &info, esr);
>  
> -	return 0;
> +	return ret;
>  }
>  
>  static const struct fault_info {
> @@ -603,6 +604,20 @@ static const char *fault_name(unsigned int esr)
>  }
>  
>  /*
> + * Handle Synchronous External Aborts that occur in a guest kernel.
> + */
> +int handle_guest_sea(unsigned long addr, unsigned int esr)
> +{
> +	int ret = -ENOENT;
> +
> +	if(IS_ENABLED(CONFIG_ACPI_APEI_SEA)) {
> +		ret = ghes_notify_sea();
> +	}
> +
> +	return ret;
> +}
> +
> +/*
>   * Dispatch a data abort to the relevant handler.
>   */
>  asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> index 230b095..81eabc6 100644
> --- a/drivers/acpi/apei/ghes.c
> +++ b/drivers/acpi/apei/ghes.c
> @@ -810,17 +810,18 @@ static int ghes_notify_sci(struct notifier_block *this,
>  #ifdef CONFIG_ACPI_APEI_SEA
>  static LIST_HEAD(ghes_sea);
>  
> -void ghes_notify_sea(void)
> +int ghes_notify_sea(void)
>  {
>  	struct ghes *ghes;
> +	int ret = -ENOENT;
>  
> -	/*
> -	 * synchronize_rcu() will wait for nmi_exit(), so no need to
> -	 * rcu_read_lock().
> -	 */
> +	rcu_read_lock();
>  	list_for_each_entry_rcu(ghes, &ghes_sea, list) {
> -		ghes_proc(ghes);
> +		if(!ghes_proc(ghes))
> +			ret = 0;
>  	}
> +	rcu_read_unlock();
> +	return ret;
>  }
>  
>  static void ghes_sea_add(struct ghes *ghes)
> diff --git a/include/acpi/ghes.h b/include/acpi/ghes.h
> index 18bc935..2a727dc 100644
> --- a/include/acpi/ghes.h
> +++ b/include/acpi/ghes.h
> @@ -99,6 +99,6 @@ static inline void *acpi_hest_generic_data_payload(struct acpi_hest_generic_data
>  		gdata + 1;
>  }
>  
> -void ghes_notify_sea(void);
> +int ghes_notify_sea(void);
>  
>  #endif /* GHES_H */
> 

Otherwise, the KVM changes look good to me. Assuming you fix the two
nits above:

Acked-by: Marc Zyngier <marc.zyngier@xxxxxxx>

Thanks,
	
	M.
-- 
Jazz is not dead. It just smells funny...
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