In the firmware-first RAS solution, corrupt data is detected in a memory location when guest OS application software executing at EL0 or guest OS kernel El1 software are reading from the memory. The memory node records errors into an accessible system registers. Because SCR_EL3.EA is 1, then CPU will trap to El3 firmware, EL3 firmware records the error to APEI table through reading system register. Because the error was taken from a lower Exception level, if the exception is SEA/SEI and HCR_EL2.TEA/HCR_EL2.AMO is 1, firmware sets ESR_EL2/FAR_EL2 to fake a exception trap to EL2, then transfers to hypervisor. For the synchronous external abort(SEA), Hypervisor calls the handle_guest_sea() to deal with this error, which will reads the APEI table to get the error physical address, then call memory_failure() to identify the this address to poisoned and deliver SIGBUS signal to userspace. The advantage of using SIGBUS signal to notify user space is that it can be compatible with Non-Kvm users. For the SError Interrupt(SEI), KVM firstly classified the error. If the SError error comes from guest and is not propagated, then call handle_guest_sei() to let host firstly handle it. If the address recorded by APEI table is valid, then deliver SIGBUS signal to user space, user space will record the address to guest APEI table. Otherwise, directly injects virtual SError, or panic if the error is fatal. Sometime the error address recorded by APEI may be invalid(not accurate), and SIGBUS is not delivered to userspace. For this case, to make sure notify guest, userspace still inject virtual SError with specify syndrome to guest. The specify syndrome will be set to the VSESR_EL2. VSESR_EL2 is a new ARMv8.2 RAS extensions register which provides the syndrome value reported to software on taking a virtual SError interrupt exception. By default specify this syndrome value to IMPLEMENTATION DEFINED, because all-zero means 'RAS error: Uncategorized' instead of 'no valid ISS'. Dongjiu Geng (4): arm64: kvm: route synchronous external abort exceptions to EL2 arm64: kvm: Introduce KVM_ARM_SET_SERROR_ESR ioctl arm64: kvm: Set Virtual SError Exception Syndrome for guest arm64: kvm: handle SEI notification for guest Documentation/virtual/kvm/api.txt | 11 +++++++ arch/arm/include/asm/kvm_host.h | 1 + arch/arm/kvm/guest.c | 9 ++++++ arch/arm64/include/asm/esr.h | 10 ++++++ arch/arm64/include/asm/kvm_arm.h | 2 ++ arch/arm64/include/asm/kvm_asm.h | 1 + arch/arm64/include/asm/kvm_emulate.h | 17 ++++++++++ arch/arm64/include/asm/kvm_host.h | 11 +++++++ arch/arm64/include/asm/sysreg.h | 13 ++++++++ arch/arm64/include/asm/system_misc.h | 2 +- arch/arm64/kvm/guest.c | 14 +++++++++ arch/arm64/kvm/handle_exit.c | 61 +++++++++++++++++++++++++++++++++--- arch/arm64/kvm/hyp/switch.c | 15 +++++++++ arch/arm64/kvm/inject_fault.c | 13 +++++++- arch/arm64/kvm/reset.c | 3 ++ arch/arm64/kvm/sys_regs.c | 40 +++++++++++++++++++++++ arch/arm64/mm/fault.c | 16 ++++++++++ include/uapi/linux/kvm.h | 3 ++ virt/kvm/arm/arm.c | 7 +++++ 19 files changed, 243 insertions(+), 6 deletions(-) -- 2.10.1
