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SubjectRe: [PATCH] kvm: pass the virtual SEI syndrome to guest OS
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On 2017/3/20 19:24, Marc Zyngier wrote:
> Please include James Morse on anything RAS related, as he's already
> looking at related patches.
>
> On 20/03/17 07:55, Dongjiu Geng wrote:
>> In the RAS implementation, hardware pass the virtual SEI
>> syndrome information through the VSESR_EL2, so set the virtual
>> SEI syndrome using physical SEI syndrome el2_elr to pass to
>> the guest OS
>>
>> Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com>
>> Signed-off-by: Quanming wu <wuquanming@huawei.com>
>> ---
>> arch/arm64/Kconfig | 8 ++++++++
>> arch/arm64/include/asm/esr.h | 1 +
>> arch/arm64/include/asm/kvm_emulate.h | 12 ++++++++++++
>> arch/arm64/include/asm/kvm_host.h | 4 ++++
>> arch/arm64/kvm/hyp/switch.c | 15 ++++++++++++++-
>> arch/arm64/kvm/inject_fault.c | 10 ++++++++++
>> 6 files changed, 49 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>> index 8c7c244247b6..ea62170a3b75 100644
>> --- a/arch/arm64/Kconfig
>> +++ b/arch/arm64/Kconfig
>> @@ -908,6 +908,14 @@ endmenu
>>
>> menu "ARMv8.2 architectural features"
>>
>> +config HAS_RAS_EXTENSION
>> + bool "Support arm64 RAS extension"
>> + default n
>> + help
>> + Reliability, Availability, Serviceability(RAS; part of the ARMv8.2 Extensions).
>> +
>> + Selecting this option OS will try to recover the error that RAS hardware node detected.
>> +
>
> As this is an architectural extension, this should be controlled by the
> CPU feature mechanism, and not be chosen at compile time. What you have
> here will break horribly when booted on a CPU that doesn't implement RAS.

thanks very much for your review, yes, it is, you are right.

>
>> config ARM64_UAO
>> bool "Enable support for User Access Override (UAO)"
>> default y
>> diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h
>> index d14c478976d0..e38d32b2bdad 100644
>> --- a/arch/arm64/include/asm/esr.h
>> +++ b/arch/arm64/include/asm/esr.h
>> @@ -111,6 +111,7 @@
>> #define ESR_ELx_COND_MASK (UL(0xF) << ESR_ELx_COND_SHIFT)
>> #define ESR_ELx_WFx_ISS_WFE (UL(1) << 0)
>> #define ESR_ELx_xVC_IMM_MASK ((1UL << 16) - 1)
>> +#define VSESR_ELx_IDS_ISS_MASK ((1UL << 25) - 1)
>>
>> /* ESR value templates for specific events */
>>
>> diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
>> index f5ea0ba70f07..20d4da7f5dce 100644
>> --- a/arch/arm64/include/asm/kvm_emulate.h
>> +++ b/arch/arm64/include/asm/kvm_emulate.h
>> @@ -148,6 +148,18 @@ static inline u32 kvm_vcpu_get_hsr(const struct kvm_vcpu *vcpu)
>> return vcpu->arch.fault.esr_el2;
>> }
>>
>> +#ifdef CONFIG_HAS_RAS_EXTENSION
>> +static inline u32 kvm_vcpu_get_vsesr(const struct kvm_vcpu *vcpu)
>> +{
>> + return vcpu->arch.fault.vsesr_el2;
>> +}
>> +
>> +static inline void kvm_vcpu_set_vsesr(struct kvm_vcpu *vcpu, unsigned long val)
>> +{
>> + vcpu->arch.fault.vsesr_el2 = val;
>> +}
>> +#endif
>> +
>> static inline int kvm_vcpu_get_condition(const struct kvm_vcpu *vcpu)
>> {
>> u32 esr = kvm_vcpu_get_hsr(vcpu);
>> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
>> index e7705e7bb07b..f9e3bb57c461 100644
>> --- a/arch/arm64/include/asm/kvm_host.h
>> +++ b/arch/arm64/include/asm/kvm_host.h
>> @@ -83,6 +83,10 @@ struct kvm_mmu_memory_cache {
>> };
>>
>> struct kvm_vcpu_fault_info {
>> +#ifdef CONFIG_HAS_RAS_EXTENSION
>> + /* Virtual SError Exception Syndrome Register */
>> + u32 vsesr_el2;
>> +#endif
>> u32 esr_el2; /* Hyp Syndrom Register */
>> u64 far_el2; /* Hyp Fault Address Register */
>> u64 hpfar_el2; /* Hyp IPA Fault Address Register */
>> diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
>> index aede1658aeda..770a153fb6ba 100644
>> --- a/arch/arm64/kvm/hyp/switch.c
>> +++ b/arch/arm64/kvm/hyp/switch.c
>> @@ -86,6 +86,13 @@ static void __hyp_text __activate_traps(struct kvm_vcpu *vcpu)
>> isb();
>> }
>> write_sysreg(val, hcr_el2);
>> +#ifdef CONFIG_HAS_RAS_EXTENSION
>> + /* If virtual System Error or Asynchronous Abort is pending. set
>> + * the virtual exception syndrome information
>> + */
>> + if (vcpu->arch.hcr_el2 & HCR_VSE)
>> + write_sysreg(vcpu->arch.fault.vsesr_el2, vsesr_el2);
>> +#endif
>> /* Trap on AArch32 cp15 c15 accesses (EL1 or EL0) */
>> write_sysreg(1 << 15, hstr_el2);
>> /*
>> @@ -139,8 +146,14 @@ static void __hyp_text __deactivate_traps(struct kvm_vcpu *vcpu)
>> * the crucial bit is "On taking a vSError interrupt,
>> * HCR_EL2.VSE is cleared to 0."
>> */
>> - if (vcpu->arch.hcr_el2 & HCR_VSE)
>> + if (vcpu->arch.hcr_el2 & HCR_VSE) {
>> vcpu->arch.hcr_el2 = read_sysreg(hcr_el2);
>> +#ifdef CONFIG_HAS_RAS_EXTENSION
>> + /* set vsesr_el2[24:0] with esr_el2[24:0] */
>> + kvm_vcpu_set_vsesr(vcpu, read_sysreg_el2(esr)
>> + & VSESR_ELx_IDS_ISS_MASK);
>
> What guarantees that ESR_EL2 still contains the latest exception? What
> does it mean to store something that is the current EL2 exception
> syndrome together with an SError that has already been injected?

yes, thanks for the review, I will add a judgement condition for the "exit_code"
if the "exit_code == ARM_EXCEPTION_EL1_SERROR" then set the vsesr_el2.

for the aarch32, it only need set the "ExT, bit [12]" and AET, "bits [15:14]", other bit is RES0

>
> Also, is it correct to directly copy the ESR_EL2 bits into VSESR_EL2? My
please see below spec description, it virtual SERROR syndrome from VSESR_EL2.
-----
 Control returns to the OS, and the ESB instruction is re-executed.
— The physical asynchronous SError interrupt has been cleared, so it is not taken again.
— The PE sets VDISR_EL2.A to 1 and records the syndrome from VSESR_EL2 in VDISR_EL2.
-----

> own reading of the specification seem to imply that there is at least
> differences when the guest is AArch32. Surely there would be some
> processing here.



>
>> +#endif
>> + }
>>
>> __deactivate_traps_arch()();
>> write_sysreg(0, hstr_el2);
>> diff --git a/arch/arm64/kvm/inject_fault.c b/arch/arm64/kvm/inject_fault.c
>> index da6a8cfa54a0..08a13dfe28a8 100644
>> --- a/arch/arm64/kvm/inject_fault.c
>> +++ b/arch/arm64/kvm/inject_fault.c
>> @@ -242,4 +242,14 @@ void kvm_inject_undefined(struct kvm_vcpu *vcpu)
>> void kvm_inject_vabt(struct kvm_vcpu *vcpu)
>> {
>> vcpu_set_hcr(vcpu, vcpu_get_hcr(vcpu) | HCR_VSE);
>> +#ifdef CONFIG_HAS_RAS_EXTENSION
>> + /* If virtual System Error or Asynchronous Abort is set. set
>> + * the virtual exception syndrome information
>> + */
>> + kvm_vcpu_set_vsesr(vcpu, ((kvm_vcpu_get_vsesr(vcpu)
>> + & (~VSESR_ELx_IDS_ISS_MASK))
>> + | (kvm_vcpu_get_hsr(vcpu)
>> + & VSESR_ELx_IDS_ISS_MASK)));
>
> What is the rational for setting VSESR_EL2 with the EL1 syndrome
> information? That doesn't make any sense to me.
thanks, I set the VSESR_EL2 using the EL2 syndrome information, "kvm_vcpu_get_hsr"
return the value of esr_el2, not EL1 syndrome information

>
> Overall, this patch is completely inconsistent and unclear in what it
> tries to achieve. Also, as I already tated before, I'd like to see the
> "firmware first" mode of operation be enforced here, going back to
> userspace and let the VMM decide what to do.
>
> Thanks,
>
> M.
>

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