kernel/linux.git/arch/powerpc/kvm/emulate.c, branch linux-4.16.y

KVM: PPC: Book3S HV: Enable guests to use large decrementer mode on POWER9

2017-06-19T04:02:04+00:00

This allows userspace (e.g. QEMU) to enable large decrementer mode for the guest when running on a POWER9 host, by setting the LPCR_LD bit in the guest LPCR value. With this, the guest exit code saves 64 bits of the guest DEC value on exit. Other places that use the guest DEC value check the LPCR_LD bit in the guest LPCR value, and if it is set, omit the 32-bit sign extension that would otherwise be done. This doesn't change the DEC emulation used by PR KVM because PR KVM is not supported on POWER9 yet. This is partly based on an earlier patch by Oliver O'Halloran. Signed-off-by: Paul Mackerras

KVM: PPC: Book3S PR: Do not fail emulation with mtspr/mfspr for unknown SPRs

2017-04-20T01:39:32+00:00

According to the PowerISA 2.07, mtspr and mfspr should not always generate an illegal instruction exception when being used with an undefined SPR, but rather treat the instruction as a NOP or inject a privilege exception in some cases, too - depending on the SPR number. Also turn the printk here into a ratelimited print statement, so that the guest can not flood the dmesg log of the host by issueing lots of illegal mtspr/mfspr instruction here. Signed-off-by: Thomas Huth Signed-off-by: Paul Mackerras

KVM: PPC: Book3S PR: Fix illegal opcode emulation

2016-06-20T04:11:25+00:00

If kvmppc_handle_exit_pr() calls kvmppc_emulate_instruction() to emulate one instruction (in the BOOK3S_INTERRUPT_H_EMUL_ASSIST case), it calls kvmppc_core_queue_program() afterwards if kvmppc_emulate_instruction() returned EMULATE_FAIL, so the guest gets an program interrupt for the illegal opcode. However, the kvmppc_emulate_instruction() also tried to inject a program exception for this already, so the program interrupt gets injected twice and the return address in srr0 gets destroyed. All other callers of kvmppc_emulate_instruction() are also injecting a program interrupt, and since the callers have the right knowledge about the srr1 flags that should be used, it is the function kvmppc_emulate_instruction() that should _not_ inject program interrupts, so remove the kvmppc_core_queue_program() here. This fixes the issue discovered by Laurent Vivier with kvm-unit-tests where the logs are filled with these messages when the test tries to execute an illegal instruction: Couldn't emulate instruction 0x00000000 (op 0 xop 0) kvmppc_handle_exit_pr: emulation at 700 failed (00000000) Signed-off-by: Thomas Huth Reviewed-by: Alexander Graf Tested-by: Laurent Vivier Signed-off-by: Paul Mackerras

KVM: PPC: Pass enum to kvmppc_get_last_inst

2014-09-22T08:11:36+00:00

The kvmppc_get_last_inst function recently received a facelift that allowed us to pass an enum of the type of instruction we want to read into it rather than an unreadable boolean. Unfortunately, not all callers ended up passing the enum. This wasn't really an issue as "true" and "false" happen to match the two enum values we have, but it's still hard to read. Update all callers of kvmppc_get_last_inst() to follow the new calling convention. Signed-off-by: Alexander Graf

powerpc/kvm: support to handle sw breakpoint

2014-09-22T08:11:35+00:00

This patch adds kernel side support for software breakpoint. Design is that, by using an illegal instruction, we trap to hypervisor via Emulation Assistance interrupt, where we check for the illegal instruction and accordingly we return to Host or Guest. Patch also adds support for software breakpoint in PR KVM. Signed-off-by: Madhavan Srinivasan Signed-off-by: Alexander Graf

KVM: PPC: Separate loadstore emulation from priv emulation

2014-07-28T16:30:10+00:00

Today the instruction emulator can get called via 2 separate code paths. It can either be called by MMIO emulation detection code or by privileged instruction traps. This is bad, as both code paths prepare the environment differently. For MMIO emulation we already know the virtual address we faulted on, so instructions there don't have to actually fetch that information. Split out the two separate use cases into separate files. Signed-off-by: Alexander Graf

KVM: PPC: Allow kvmppc_get_last_inst() to fail

2014-07-28T13:23:14+00:00

On book3e, guest last instruction is read on the exit path using load external pid (lwepx) dedicated instruction. This load operation may fail due to TLB eviction and execute-but-not-read entries. This patch lay down the path for an alternative solution to read the guest last instruction, by allowing kvmppc_get_lat_inst() function to fail. Architecture specific implmentations of kvmppc_load_last_inst() may read last guest instruction and instruct the emulation layer to re-execute the guest in case of failure. Make kvmppc_get_last_inst() definition common between architectures. Signed-off-by: Mihai Caraman Signed-off-by: Alexander Graf

KVM: PPC: Make shared struct aka magic page guest endian

2014-05-30T12:26:21+00:00

The shared (magic) page is a data structure that contains often used supervisor privileged SPRs accessible via memory to the user to reduce the number of exits we have to take to read/write them. When we actually share this structure with the guest we have to maintain it in guest endianness, because some of the patch tricks only work with native endian load/store operations. Since we only share the structure with either host or guest in little endian on book3s_64 pr mode, we don't have to worry about booke or book3s hv. For booke, the shared struct stays big endian. For book3s_64 hv we maintain the struct in host native endian, since it never gets shared with the guest. For book3s_64 pr we introduce a variable that tells us which endianness the shared struct is in and route every access to it through helper inline functions that evaluate this variable. Signed-off-by: Alexander Graf

KVM: PPC: Book3S: MMIO emulation support for little endian guests

2014-01-27T15:00:39+00:00

MMIO emulation reads the last instruction executed by the guest and then emulates. If the guest is running in Little Endian order, or more generally in a different endian order of the host, the instruction needs to be byte-swapped before being emulated. This patch adds a helper routine which tests the endian order of the host and the guest in order to decide whether a byteswap is needed or not. It is then used to byteswap the last instruction of the guest in the endian order of the host before MMIO emulation is performed. Finally, kvmppc_handle_load() of kvmppc_handle_store() are modified to reverse the endianness of the MMIO if required. Signed-off-by: Cédric Le Goater [agraf: add booke handling] Signed-off-by: Alexander Graf

kvm: powerpc: book3s: Allow the HV and PR selection per virtual machine

2013-10-17T16:42:36+00:00

This moves the kvmppc_ops callbacks to be a per VM entity. This enables us to select HV and PR mode when creating a VM. We also allow both kvm-hv and kvm-pr kernel module to be loaded. To achieve this we move /dev/kvm ownership to kvm.ko module. Depending on which KVM mode we select during VM creation we take a reference count on respective module Signed-off-by: Aneesh Kumar K.V [agraf: fix coding style] Signed-off-by: Alexander Graf