Re: [PATCH V7 10/10] arm/arm64: KVM: add guest SEA support
From: Baicar, Tyler
Date: Mon Jan 16 2017 - 15:14:56 EST
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 <tbaicar@xxxxxxxxxxxxxx>
---
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 <asm/kvm_asm.h>
#include <asm/kvm_emulate.h>
#include <asm/virt.h>
+#include <asm/system_misc.h>
#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_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(&sea_handler_chain, 0, NULL);
+
+ pr_err("Synchronous External Abort: %s (0x%08x) at 0x%016lx\n",
+ fault_name(esr), esr, addr);
Same here.
I will remove this print.
+
+ return 0;
+}
+
+/*
* Dispatch a data abort to the relevant handler.
*/
asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
Thanks,
M.
Thanks,
Tyler
--
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