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 in an error record accessible using 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 ghes_handle_memory_failure() to deal with this error, ghes_handle_memory_failure() function reads the APEI table and callls memory_failure() to decide whether it needs to deliver SIGBUS signal to user space, 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. Not call memory_failure() to handle it. Because the error address recorded by APEI is not accurated, so can not identify the address to hwpoison memory. If the SError error comes from guest user mode and is not propagated, then signal user space to handle it, otherwise, directly injects virtual SError, or panic if the error is fatal. when user space handles the error, it will specify syndrome for the injected virtual SError. This syndrome value is 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. Dongjiu Geng (5): acpi: apei: remove the unused code arm64: kvm: support user space to query RAS extension feature arm64: kvm: route synchronous external abort exceptions to el2 KVM: arm64: allow get exception information from userspace arm64: kvm: handle SEI notification and pass the virtual syndrome James Morse (1): KVM: arm64: Save ESR_EL2 on guest SError Xie XiuQi (1): arm64: cpufeature: Detect CPU RAS Extentions arch/arm/include/asm/kvm_host.h | 2 ++ arch/arm/kvm/guest.c | 9 ++++++ arch/arm64/Kconfig | 16 +++++++++++ arch/arm64/include/asm/barrier.h | 1 + arch/arm64/include/asm/cpucaps.h | 3 +- arch/arm64/include/asm/esr.h | 11 +++++++ arch/arm64/include/asm/kvm_arm.h | 2 ++ arch/arm64/include/asm/kvm_emulate.h | 17 +++++++++++ arch/arm64/include/asm/kvm_host.h | 2 ++ arch/arm64/include/asm/sysreg.h | 5 ++++ arch/arm64/include/asm/system_misc.h | 1 + arch/arm64/include/uapi/asm/kvm.h | 5 ++++ arch/arm64/kernel/cpufeature.c | 13 +++++++++ arch/arm64/kernel/process.c | 3 ++ arch/arm64/kvm/guest.c | 50 ++++++++++++++++++++++++++++++++ arch/arm64/kvm/handle_exit.c | 56 ++++++++++++++++++++++++++++++++---- arch/arm64/kvm/hyp/switch.c | 29 +++++++++++++++++-- arch/arm64/kvm/reset.c | 3 ++ arch/arm64/mm/fault.c | 34 ++++++++++++++++++++++ drivers/acpi/apei/ghes.c | 14 --------- include/uapi/linux/kvm.h | 3 ++ virt/kvm/arm/arm.c | 7 +++++ 22 files changed, 263 insertions(+), 23 deletions(-) -- 2.14.1
