kernel.git/arch/arm64/include/asm/sysreg.h, branch linux-4.16.y

KVM: arm64: Emulate RAS error registers and set HCR_EL2's TERR & TEA

2018-01-16T15:09:47Z

ARMv8.2 adds a new bit HCR_EL2.TEA which routes synchronous external aborts to EL2, and adds a trap control bit HCR_EL2.TERR which traps all Non-secure EL1&0 error record accesses to EL2. This patch enables the two bits for the guest OS, guaranteeing that KVM takes external aborts and traps attempts to access the physical error registers. ERRIDR_EL1 advertises the number of error records, we return zero meaning we can treat all the other registers as RAZ/WI too. Signed-off-by: Dongjiu Geng [removed specific emulation, use trap_raz_wi() directly for everything, rephrased parts of the commit message] Signed-off-by: James Morse Reviewed-by: Christoffer Dall Reviewed-by: Marc Zyngier Signed-off-by: Catalin Marinas

KVM: arm64: Save/Restore guest DISR_EL1

2018-01-16T15:08:52Z

If we deliver a virtual SError to the guest, the guest may defer it with an ESB instruction. The guest reads the deferred value via DISR_EL1, but the guests view of DISR_EL1 is re-mapped to VDISR_EL2 when HCR_EL2.AMO is set. Add the KVM code to save/restore VDISR_EL2, and make it accessible to userspace as DISR_EL1. Signed-off-by: James Morse Reviewed-by: Marc Zyngier Reviewed-by: Christoffer Dall Signed-off-by: Catalin Marinas

KVM: arm64: Set an impdef ESR for Virtual-SError using VSESR_EL2.

2018-01-16T15:08:41Z

Prior to v8.2's RAS Extensions, the HCR_EL2.VSE 'virtual SError' feature generated an SError with an implementation defined ESR_EL1.ISS, because we had no mechanism to specify the ESR value. On Juno this generates an all-zero ESR, the most significant bit 'ISV' is clear indicating the remainder of the ISS field is invalid. With the RAS Extensions we have a mechanism to specify this value, and the most significant bit has a new meaning: 'IDS - Implementation Defined Syndrome'. An all-zero SError ESR now means: 'RAS error: Uncategorized' instead of 'no valid ISS'. Add KVM support for the VSESR_EL2 register to specify an ESR value when HCR_EL2.VSE generates a virtual SError. Change kvm_inject_vabt() to specify an implementation-defined value. We only need to restore the VSESR_EL2 value when HCR_EL2.VSE is set, KVM save/restores this bit during __{,de}activate_traps() and hardware clears the bit once the guest has consumed the virtual-SError. Future patches may add an API (or KVM CAP) to pend a virtual SError with a specified ESR. Cc: Dongjiu Geng Reviewed-by: Marc Zyngier Signed-off-by: James Morse Reviewed-by: Christoffer Dall Signed-off-by: Catalin Marinas

arm64: kernel: Prepare for a DISR user

2018-01-16T15:07:12Z

KVM would like to consume any pending SError (or RAS error) after guest exit. Today it has to unmask SError and use dsb+isb to synchronise the CPU. With the RAS extensions we can use ESB to synchronise any pending SError. Add the necessary macros to allow DISR to be read and converted to an ESR. We clear the DISR register when we enable the RAS cpufeature, and the kernel has not executed any ESB instructions. Any value we find in DISR must have belonged to firmware. Executing an ESB instruction is the only way to update DISR, so we can expect firmware to have handled any deferred SError. By the same logic we clear DISR in the idle path. Reviewed-by: Suzuki K Poulose Signed-off-by: James Morse Reviewed-by: Catalin Marinas Signed-off-by: Catalin Marinas

arm64: Unconditionally enable IESB on exception entry/return for firmware-first

2018-01-16T15:06:45Z

ARM v8.2 has a feature to add implicit error synchronization barriers whenever the CPU enters or returns from an exception level. Add this to the features we always enable. CPUs that don't support this feature will treat the bit as RES0. This feature causes RAS errors that are not yet visible to software to become pending SErrors. We expect to have firmware-first RAS support so synchronised RAS errors will be take immediately to EL3. Any system without firmware-first handling of errors will take the SError either immediatly after exception return, or when we unmask SError after entry.S's work. Adding IESB to the ELx flags causes it to be enabled by KVM and kexec too. Platform level RAS support may require additional firmware support. Cc: Christoffer Dall Suggested-by: Will Deacon Link: https://www.spinics.net/lists/kvm-arm/msg28192.html Acked-by: Marc Zyngier Signed-off-by: James Morse Signed-off-by: Catalin Marinas

arm64: cpufeature: Detect CPU RAS Extentions

2018-01-16T15:05:48Z

ARM's v8.2 Extentions add support for Reliability, Availability and Serviceability (RAS). On CPUs with these extensions system software can use additional barriers to isolate errors and determine if faults are pending. Add cpufeature detection. Platform level RAS support may require additional firmware support. Reviewed-by: Suzuki K Poulose Signed-off-by: Xie XiuQi [Rebased added config option, reworded commit message] Signed-off-by: James Morse Reviewed-by: Catalin Marinas Signed-off-by: Catalin Marinas

arm64: sysreg: Move to use definitions for all the SCTLR bits

2018-01-16T15:05:39Z

__cpu_setup() configures SCTLR_EL1 using some hard coded hex masks, and el2_setup() duplicates some this when setting RES1 bits. Lets make this the same as KVM's hyp_init, which uses named bits. First, we add definitions for all the SCTLR_EL{1,2} bits, the RES{1,0} bits, and those we want to set or clear. Add a build_bug checks to ensures all bits are either set or clear. This means we don't need to preserve endian-ness configuration generated elsewhere. Finally, move the head.S and proc.S users of these hard-coded masks over to the macro versions. Signed-off-by: James Morse Signed-off-by: Catalin Marinas

arm64: Add skeleton to harden the branch predictor against aliasing attacks

2018-01-08T18:45:25Z

Aliasing attacks against CPU branch predictors can allow an attacker to redirect speculative control flow on some CPUs and potentially divulge information from one context to another. This patch adds initial skeleton code behind a new Kconfig option to enable implementation-specific mitigations against these attacks for CPUs that are affected. Co-developed-by: Marc Zyngier Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas

arm64: Take into account ID_AA64PFR0_EL1.CSV3

2018-01-08T18:43:34Z

For non-KASLR kernels where the KPTI behaviour has not been overridden on the command line we can use ID_AA64PFR0_EL1.CSV3 to determine whether or not we should unmap the kernel whilst running at EL0. Reviewed-by: Suzuki K Poulose Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas

arm64: v8.4: Support for new floating point multiplication instructions

2018-01-05T11:29:48Z

ARM v8.4 extensions add new neon instructions for performing a multiplication of each FP16 element of one vector with the corresponding FP16 element of a second vector, and to add or subtract this without an intermediate rounding to the corresponding FP32 element in a third vector. This patch detects this feature and let the userspace know about it via a HWCAP bit and MRS emulation. Cc: Dave Martin Reviewed-by: Suzuki K Poulose Signed-off-by: Dongjiu Geng Reviewed-by: Dave Martin Signed-off-by: Catalin Marinas