Re: [PATCH V7 10/10] arm/arm64: KVM: add guest SEA support

[Baicar, Tyler]

Hello Marc,


On 1/16/2017 4:58 AM, Marc Zyngier wrote:

Hi Tyler,

On 12/01/17 18:15, 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 
---
  arch/arm/include/asm/kvm_arm.h   |  1 +
  arch/arm/include/asm/system_misc.h   |  5 +
  arch/arm/kvm/mmu.c   | 18 --
  arch/arm64/include/asm/kvm_arm.h |  1 +
  arch/arm64/include/asm/system_misc.h |  2 ++
  arch/arm64/mm/fault.c| 13 +
  6 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/arch/arm/include/asm/kvm_arm.h b/arch/arm/include/asm/kvm_arm.h
index e22089f..33a77509 100644
--- a/arch/arm/include/asm/kvm_arm.h
+++ b/arch/arm/include/asm/kvm_arm.h
@@ -187,6 +187,7 @@
  #define FSC_FAULT (0x04)
  #define FSC_ACCESS(0x08)
  #define FSC_PERM  (0x0c)
+#define FSC_EXTABT (0x10)
  
  /* 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 @@ extern unsigned int user_debug;
  
  #endif /* !__ASSEMBLY__ */
  
+static inline int handle_guest_sea(unsigned long addr, unsigned int esr)

+{
+   return -1;
+}
+
  #endif /* __ASM_ARM_SYSTEM_MISC_H */
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index e9a5c0e..1152966 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -29,6 +29,7 @@
  #include 
  #include 
  #include 
+#include 
  
  #include "trace.h"
  
@@ -1441,8 +1442,21 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run)
  
  	/* 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) {
+
+   /* The host kernel will handle the synchronous external abort. There
+* is no need to pass the error into the guest.
+*/
+   if (fault_status == FSC_EXTABT) {
+   if(handle_guest_sea((unsigned long)fault_ipa,
+   kvm_vcpu_get_hsr(vcpu))) {
+   kvm_err("Failed to handle guest SEA, FSC: EC=%#x xFSC=%#lx 
ESR_EL2=%#lx\n",
+   kvm_vcpu_trap_get_class(vcpu),
+   (unsigned long)kvm_vcpu_trap_get_fault(vcpu),
+   (unsigned long)kvm_vcpu_get_hsr(vcpu));

So there's one thing I don't like here, which is that we just gave the
guest a very nice way to pollute the host's kernel log with spurious
messages. So I'd rather make it silent, or at the very least rate limited.
Before this patch, if a guest exits with FSC_EXTABT, then the below 
print for
"Unsupported FSC..." would happen. So this print isn't really adding any 
noise
that isn't already there. Also, this print would only happen if 
handle_guest_sea
fails. If you still think this print should be removed then I will 
remove it though.

+   return -EFAULT;
+   }
+   } else if (fault_status != FSC_FAULT && fault_status != FSC_PERM &&
+  fault_status != FSC_ACCESS) {
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 4b5c977..be0efb6 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -201,6 +201,7 @@
  #define FSC_FAULT ESR_ELx_FSC_FAULT
  #define FSC_ACCESSESR_ELx_FSC_ACCESS
  #define FSC_PERM  ESR_ELx_FSC_PERM
+#define FSC_EXTABT ESR_ELx_FSC_EXTABT
  
  /* 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 e7f3440..27816cb 100644
--- a/arch/arm64/include/asm/system_misc.h
+++ b/arch/arm64/include/asm/system_misc.h
@@ -77,4 +77,6 @@ extern void (*arm_pm_restart)(enum reboot_mode reboot_mode, 
const char *cmd);
  int register_sea_notifier(struct notifier_block *nb);
  void unregister_sea_notifier(struct notifier_block *nb);
  
+int handle_guest_sea(unsigned long addr, unsigned int esr);

+
  #endif/* __ASM_SYSTEM_MISC_H */
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 81039c7..fa8d4d7 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -597,6 +597,19 @@ 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, 

Re: [PATCH V7 10/10] arm/arm64: KVM: add guest SEA support

[Marc Zyngier]

Hi Tyler,

On 12/01/17 18:15, 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 
> ---
>  arch/arm/include/asm/kvm_arm.h   |  1 +
>  arch/arm/include/asm/system_misc.h   |  5 +
>  arch/arm/kvm/mmu.c   | 18 --
>  arch/arm64/include/asm/kvm_arm.h |  1 +
>  arch/arm64/include/asm/system_misc.h |  2 ++
>  arch/arm64/mm/fault.c| 13 +
>  6 files changed, 38 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm/include/asm/kvm_arm.h b/arch/arm/include/asm/kvm_arm.h
> index e22089f..33a77509 100644
> --- a/arch/arm/include/asm/kvm_arm.h
> +++ b/arch/arm/include/asm/kvm_arm.h
> @@ -187,6 +187,7 @@
>  #define FSC_FAULT(0x04)
>  #define FSC_ACCESS   (0x08)
>  #define FSC_PERM (0x0c)
> +#define FSC_EXTABT   (0x10)
>  
>  /* 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 @@ extern unsigned int user_debug;
>  
>  #endif /* !__ASSEMBLY__ */
>  
> +static inline int handle_guest_sea(unsigned long addr, unsigned int esr)
> +{
> + return -1;
> +}
> +
>  #endif /* __ASM_ARM_SYSTEM_MISC_H */
> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> index e9a5c0e..1152966 100644
> --- a/arch/arm/kvm/mmu.c
> +++ b/arch/arm/kvm/mmu.c
> @@ -29,6 +29,7 @@
>  #include 
>  #include 
>  #include 
> +#include 
>  
>  #include "trace.h"
>  
> @@ -1441,8 +1442,21 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, 
> struct kvm_run *run)
>  
>   /* 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) {
> +
> + /* The host kernel will handle the synchronous external abort. There
> +  * is no need to pass the error into the guest.
> +  */
> + if (fault_status == FSC_EXTABT) {
> + if(handle_guest_sea((unsigned long)fault_ipa,
> + kvm_vcpu_get_hsr(vcpu))) {
> + kvm_err("Failed to handle guest SEA, FSC: EC=%#x 
> xFSC=%#lx ESR_EL2=%#lx\n",
> + kvm_vcpu_trap_get_class(vcpu),
> + (unsigned long)kvm_vcpu_trap_get_fault(vcpu),
> + (unsigned long)kvm_vcpu_get_hsr(vcpu));

So there's one thing I don't like here, which is that we just gave the
guest a very nice way to pollute the host's kernel log with spurious
messages. So I'd rather make it silent, or at the very least rate limited.

> + return -EFAULT;
> + }
> + } else if (fault_status != FSC_FAULT && fault_status != FSC_PERM &&
> +fault_status != FSC_ACCESS) {
>   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 4b5c977..be0efb6 100644
> --- a/arch/arm64/include/asm/kvm_arm.h
> +++ b/arch/arm64/include/asm/kvm_arm.h
> @@ -201,6 +201,7 @@
>  #define FSC_FAULTESR_ELx_FSC_FAULT
>  #define FSC_ACCESS   ESR_ELx_FSC_ACCESS
>  #define FSC_PERM ESR_ELx_FSC_PERM
> +#define FSC_EXTABT   ESR_ELx_FSC_EXTABT
>  
>  /* 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 e7f3440..27816cb 100644
> --- a/arch/arm64/include/asm/system_misc.h
> +++ b/arch/arm64/include/asm/system_misc.h
> @@ -77,4 +77,6 @@ extern void (*arm_pm_restart)(enum reboot_mode reboot_mode, 
> const char *cmd);
>  int register_sea_notifier(struct notifier_block *nb);
>  void unregister_sea_notifier(struct notifier_block *nb);
>  
> +int handle_guest_sea(unsigned long addr, unsigned int esr);
> +
>  #endif   /* __ASM_SYSTEM_MISC_H */
> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> index 81039c7..fa8d4d7 100644
> --- a/arch/arm64/mm/fault.c
> +++ b/arch/arm64/mm/fault.c
> @@ -597,6 +597,19 @@ 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)
> +{
> + atomic_notifier_call_chain(_handler_chain, 0, NULL);
> +
> + pr_err("Synchronous External Abort: %s (0x%08x) at 0x%016lx\n",
> + fault_name(esr), esr, addr);

Same here.

> +
> + return 0;
> +}
> +
> 

[PATCH V7 10/10] arm/arm64: KVM: add guest SEA support

[Tyler Baicar]

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 
---
 arch/arm/include/asm/kvm_arm.h   |  1 +
 arch/arm/include/asm/system_misc.h   |  5 +
 arch/arm/kvm/mmu.c   | 18 --
 arch/arm64/include/asm/kvm_arm.h |  1 +
 arch/arm64/include/asm/system_misc.h |  2 ++
 arch/arm64/mm/fault.c| 13 +
 6 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/arch/arm/include/asm/kvm_arm.h b/arch/arm/include/asm/kvm_arm.h
index e22089f..33a77509 100644
--- a/arch/arm/include/asm/kvm_arm.h
+++ b/arch/arm/include/asm/kvm_arm.h
@@ -187,6 +187,7 @@
 #define FSC_FAULT  (0x04)
 #define FSC_ACCESS (0x08)
 #define FSC_PERM   (0x0c)
+#define FSC_EXTABT (0x10)
 
 /* 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 @@ extern unsigned int user_debug;
 
 #endif /* !__ASSEMBLY__ */
 
+static inline int handle_guest_sea(unsigned long addr, unsigned int esr)
+{
+   return -1;
+}
+
 #endif /* __ASM_ARM_SYSTEM_MISC_H */
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index e9a5c0e..1152966 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -29,6 +29,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include "trace.h"
 
@@ -1441,8 +1442,21 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct 
kvm_run *run)
 
/* 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) {
+
+   /* The host kernel will handle the synchronous external abort. There
+* is no need to pass the error into the guest.
+*/
+   if (fault_status == FSC_EXTABT) {
+   if(handle_guest_sea((unsigned long)fault_ipa,
+   kvm_vcpu_get_hsr(vcpu))) {
+   kvm_err("Failed to handle guest SEA, FSC: EC=%#x 
xFSC=%#lx ESR_EL2=%#lx\n",
+   kvm_vcpu_trap_get_class(vcpu),
+   (unsigned long)kvm_vcpu_trap_get_fault(vcpu),
+   (unsigned long)kvm_vcpu_get_hsr(vcpu));
+   return -EFAULT;
+   }
+   } else if (fault_status != FSC_FAULT && fault_status != FSC_PERM &&
+  fault_status != FSC_ACCESS) {
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 4b5c977..be0efb6 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -201,6 +201,7 @@
 #define FSC_FAULT  ESR_ELx_FSC_FAULT
 #define FSC_ACCESS ESR_ELx_FSC_ACCESS
 #define FSC_PERM   ESR_ELx_FSC_PERM
+#define FSC_EXTABT ESR_ELx_FSC_EXTABT
 
 /* 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 e7f3440..27816cb 100644
--- a/arch/arm64/include/asm/system_misc.h
+++ b/arch/arm64/include/asm/system_misc.h
@@ -77,4 +77,6 @@ extern void (*arm_pm_restart)(enum reboot_mode reboot_mode, 
const char *cmd);
 int register_sea_notifier(struct notifier_block *nb);
 void unregister_sea_notifier(struct notifier_block *nb);
 
+int handle_guest_sea(unsigned long addr, unsigned int esr);
+
 #endif /* __ASM_SYSTEM_MISC_H */
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 81039c7..fa8d4d7 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -597,6 +597,19 @@ 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)
+{
+   atomic_notifier_call_chain(_handler_chain, 0, NULL);
+
+   pr_err("Synchronous External Abort: %s (0x%08x) at 0x%016lx\n",
+   fault_name(esr), esr, addr);
+
+   return 0;
+}
+
+/*
  * Dispatch a data abort to the relevant handler.
  */
 asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
-- 
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Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum,
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