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

From: Marc Zyngier
Date: Fri Mar 24 2017 - 10:03:39 EST

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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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Previous message: Arushi Singhal: "[PATCH] staging: iio: Remove extra Parenthesis."
Next in thread: Baicar, Tyler: "Re: [PATCH V13 10/10] arm/arm64: KVM: add guest SEA support"
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