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Message-ID: <3175d58f-1820-32c1-acf7-1f591619a21f@codeaurora.org>
Date: Mon, 16 Jan 2017 13:14:06 -0700
From: "Baicar, Tyler" <tbaicar@...eaurora.org>
To: Marc Zyngier <marc.zyngier@....com>, christoffer.dall@...aro.org,
pbonzini@...hat.com, rkrcmar@...hat.com, linux@...linux.org.uk,
catalin.marinas@....com, will.deacon@....com, rjw@...ysocki.net,
lenb@...nel.org, matt@...eblueprint.co.uk, robert.moore@...el.com,
lv.zheng@...el.com, nkaje@...eaurora.org, zjzhang@...eaurora.org,
mark.rutland@....com, james.morse@....com,
akpm@...ux-foundation.org, eun.taik.lee@...sung.com,
sandeepa.s.prabhu@...il.com, labbott@...hat.com,
shijie.huang@....com, rruigrok@...eaurora.org,
paul.gortmaker@...driver.com, tn@...ihalf.com, fu.wei@...aro.org,
rostedt@...dmis.org, bristot@...hat.com,
linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-acpi@...r.kernel.org, linux-efi@...r.kernel.org,
devel@...ica.org, Suzuki.Poulose@....com, punit.agrawal@....com,
astone@...hat.com, harba@...eaurora.org, hanjun.guo@...aro.org,
john.garry@...wei.com, shiju.jose@...wei.com
Subject: Re: [PATCH V7 10/10] arm/arm64: KVM: add guest SEA support
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@...eaurora.org>
>> ---
>> 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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