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Date: Tue, 2 May 2017 20:20:18 +0800
From: gengdongjiu <gengdongjiu@...wei.com>
To: Christoffer Dall <cdall@...aro.org>
CC: <james.morse@....com>, <marc.zyngier@....com>,
<christoffer.dall@...aro.org>, <rkrcmar@...hat.com>,
<linux@...linux.org.uk>, <tbaicar@...eaurora.org>,
<imammedo@...hat.com>, <zhaoshenglong@...wei.com>,
<peter.maydell@...aro.org>, <pbonzini@...hat.com>,
<qemu-devel@...gnu.org>, <qemu-arm@...gnu.org>,
<lersek@...hat.com>, <ard.biesheuvel@...aro.org>,
<mtsirkin@...hat.com>, <drjones@...hat.com>,
<ben@...portsystems.com>, <kvm@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<kvmarm@...ts.cs.columbia.edu>, <xiexiuqi@...wei.com>,
<wangxiongfeng2@...wei.com>, <songwenjun@...wei.com>,
<wuquanming@...wei.com>, <huangshaoyu@...wei.com>,
<linux-kernel@...r.kernel.org>,
gengdongjiu <gengdongjiu@...wei.com>
Subject: Re: [PATCH v3 2/3] arm64: kvm: inject SError with virtual syndrome
Hello Christoffer.
On 2017/5/2 16:03, Christoffer Dall wrote:
> On Sun, Apr 30, 2017 at 01:37:56PM +0800, Dongjiu Geng wrote:
>> when SError happen, kvm notifies kvmtool to generate GHES table
>> to record the error, then kvmtools inject the SError with specified
>
> again, is this really specific to kvmtool? Pleae try to explain this
> mechanism in generic terms.
It is both for qemu and other userspace application. I will correct it.
>
>> virtual syndrome. when switch to guest, a virtual SError will happen with
>> this specified syndrome.
>>
>> Signed-off-by: Dongjiu Geng <gengdongjiu@...wei.com>
>> ---
>> arch/arm64/include/asm/esr.h | 2 ++
>> arch/arm64/include/asm/kvm_emulate.h | 10 ++++++++++
>> arch/arm64/include/asm/kvm_host.h | 1 +
>> arch/arm64/include/asm/sysreg.h | 3 +++
>> arch/arm64/kvm/handle_exit.c | 25 +++++++++++++++++++------
>> arch/arm64/kvm/hyp/switch.c | 15 ++++++++++++++-
>> include/uapi/linux/kvm.h | 5 +++++
>> 7 files changed, 54 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h
>> index 22f9c90..d009c99 100644
>> --- a/arch/arm64/include/asm/esr.h
>> +++ b/arch/arm64/include/asm/esr.h
>> @@ -127,6 +127,8 @@
>> #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 */
>>
>> /* BRK instruction trap from AArch64 state */
>> diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
>> index f5ea0ba..a3259a9 100644
>> --- a/arch/arm64/include/asm/kvm_emulate.h
>> +++ b/arch/arm64/include/asm/kvm_emulate.h
>> @@ -148,6 +148,16 @@ static inline u32 kvm_vcpu_get_hsr(const struct kvm_vcpu *vcpu)
>> return vcpu->arch.fault.esr_el2;
>> }
>>
>> +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;
>> +}
>> +
>> 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 e7705e7..84ed239 100644
>> --- a/arch/arm64/include/asm/kvm_host.h
>> +++ b/arch/arm64/include/asm/kvm_host.h
>> @@ -86,6 +86,7 @@ struct kvm_vcpu_fault_info {
>> u32 esr_el2; /* Hyp Syndrom Register */
>> u64 far_el2; /* Hyp Fault Address Register */
>> u64 hpfar_el2; /* Hyp IPA Fault Address Register */
>> + u32 vsesr_el2; /* Virtual SError Exception Syndrome Register */
>> };
>>
>> /*
>> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
>> index 32964c7..b6afb7a 100644
>> --- a/arch/arm64/include/asm/sysreg.h
>> +++ b/arch/arm64/include/asm/sysreg.h
>> @@ -125,6 +125,9 @@
>> #define REG_PSTATE_PAN_IMM sys_reg(0, 0, 4, 0, 4)
>> #define REG_PSTATE_UAO_IMM sys_reg(0, 0, 4, 0, 3)
>>
>> +#define VSESR_EL2 sys_reg(3, 4, 5, 2, 3)
>> +
>> +
>> #define SET_PSTATE_PAN(x) __emit_inst(0xd5000000 | REG_PSTATE_PAN_IMM | \
>> (!!x)<<8 | 0x1f)
>> #define SET_PSTATE_UAO(x) __emit_inst(0xd5000000 | REG_PSTATE_UAO_IMM | \
>> diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
>> index c89d83a..3d024a9 100644
>> --- a/arch/arm64/kvm/handle_exit.c
>> +++ b/arch/arm64/kvm/handle_exit.c
>> @@ -180,7 +180,11 @@ static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)
>>
>> static int kvm_handle_guest_sei(struct kvm_vcpu *vcpu, struct kvm_run *run)
>> {
>> - unsigned long fault_ipa = kvm_vcpu_get_fault_ipa(vcpu);
>> + unsigned long hva, fault_ipa = kvm_vcpu_get_fault_ipa(vcpu);
>> + struct kvm_memory_slot *memslot;
>> + int hsr, ret = 1;
>> + bool writable;
>> + gfn_t gfn;
>>
>> if (handle_guest_sei((unsigned long)fault_ipa,
>> kvm_vcpu_get_hsr(vcpu))) {
>> @@ -190,9 +194,20 @@ static int kvm_handle_guest_sei(struct kvm_vcpu *vcpu, struct kvm_run *run)
>> (unsigned long)kvm_vcpu_get_hsr(vcpu));
>>
>> kvm_inject_vabt(vcpu);
>> + } else {
>> + hsr = kvm_vcpu_get_hsr(vcpu);
>> +
>> + gfn = fault_ipa >> PAGE_SHIFT;
>> + memslot = gfn_to_memslot(vcpu->kvm, gfn);
>> + hva = gfn_to_hva_memslot_prot(memslot, gfn, &writable);
>> +
>> + run->exit_reason = KVM_EXIT_INTR;
>> + run->intr.syndrome_info = hsr;
>> + run->intr.address = hva;
>> + ret = 0;
>> }
>>
>> - return 0;
>> + return ret;
>> }
>>
>> /*
>> @@ -218,8 +233,7 @@ int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
>> *vcpu_pc(vcpu) -= adj;
>> }
>>
>> - kvm_handle_guest_sei(vcpu, run);
>> - return 1;
>> + return kvm_handle_guest_sei(vcpu, run);
>> }
>>
>> exception_index = ARM_EXCEPTION_CODE(exception_index);
>> @@ -228,8 +242,7 @@ int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
>> case ARM_EXCEPTION_IRQ:
>> return 1;
>> case ARM_EXCEPTION_EL1_SERROR:
>> - kvm_handle_guest_sei(vcpu, run);
>> - return 1;
>> + return kvm_handle_guest_sei(vcpu, run);
>> case ARM_EXCEPTION_TRAP:
>> /*
>> * See ARM ARM B1.14.1: "Hyp traps on instructions
>> diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
>> index aede165..ded6211 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);
>> + /* If virtual System Error or Asynchronous Abort is pending. set
>
> nit: I think you want a comma after pending, not a dot.
>
>> + * the virtual exception syndrome information
>> + */
>
> nit: commenting style
>
>> + if (cpus_have_cap(ARM64_HAS_RAS_EXTN) &&
>> + (vcpu->arch.hcr_el2 & HCR_VSE))
>> + write_sysreg_s(vcpu->arch.fault.vsesr_el2, VSESR_EL2);
>> +
>> /* Trap on AArch32 cp15 c15 accesses (EL1 or EL0) */
>> write_sysreg(1 << 15, hstr_el2);
>> /*
>> @@ -139,9 +146,15 @@ 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);
>>
>> + if (cpus_have_cap(ARM64_HAS_RAS_EXTN)) {
>> + /* set vsesr_el2[24:0] with esr_el2[24:0] */
>> + kvm_vcpu_set_vsesr(vcpu, read_sysreg_el2(esr)
>> + & VSESR_ELx_IDS_ISS_MASK);
>> + }
>> + }
>> __deactivate_traps_arch()();
>> write_sysreg(0, hstr_el2);
>> write_sysreg(0, pmuserenr_el0);
>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>> index 27fe556..bb02909 100644
>> --- a/include/uapi/linux/kvm.h
>> +++ b/include/uapi/linux/kvm.h
>> @@ -360,6 +360,11 @@ struct kvm_run {
>> struct {
>> __u8 vector;
>> } eoi;
>> + /* KVM_EXIT_INTR */
>> + struct {
>> + __u32 syndrome_info;
>> + __u64 address;
>> + } intr;
>
> definitely, not. KVM_EXIT_INTR is a generic exit code to tell userspace
> that we exited because we needed to deliver a signal or something else
> related to an asynchronous event. This implies that the syndrome_info
> etc. always has valid values on all architectures when exiting with
> KVM_EXIT_INTR.
>
> Either document the behavior as the syndrome_info has side-channel
> information on every exit, or on some KVM_EXIT_INTR exits, as we explain
> in the KVM_CAP_ARM_USER_IRQ ABI that was just added, or dedicate an
> access code.
OK.
>
>> /* KVM_EXIT_HYPERV */
>> struct kvm_hyperv_exit hyperv;
>> /* Fix the size of the union. */
>> --
>> 2.10.1
>>
>
> I'll look at the details of such patches once the ABI is clear and
> well-documented.
OK.
>
> Thanks,
> -Christoffer
>
> .
>
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