diff options
author | James Hogan <james.hogan@imgtec.com> | 2015-04-23 16:54:35 +0100 |
---|---|---|
committer | James Hogan <james.hogan@imgtec.com> | 2017-02-03 15:21:07 +0000 |
commit | 6a97c775ff77fb7c54adc3f7944205ae66cb5475 (patch) | |
tree | 7674922cbe9e70ed7ceb478e1b90c4c31ae8ab4e | |
parent | 122e51d47418f74a69a93bf02f5535d11ff75bf5 (diff) | |
download | linux-6a97c775ff77fb7c54adc3f7944205ae66cb5475.tar.bz2 |
KVM: MIPS: Use CP0_BadInstr[P] for emulation
When exiting from the guest, store the values of the CP0_BadInstr and
CP0_BadInstrP registers if they exist, which contain the encodings of
the instructions which caused the last synchronous exception.
When the instruction is needed for emulation, kvm_get_badinstr() and
kvm_get_badinstrp() are used instead of calling kvm_get_inst() directly,
to decide whether to read the saved CP0_BadInstr/CP0_BadInstrP registers
(if they exist), or read the instruction from memory (if not).
The use of these registers should be more robust than using
kvm_get_inst(), as it actually gives the instruction encoding seen by
the hardware rather than relying on user accessors after the fact, which
can be fooled by incoherent icache or a racing code modification. It
will also work with VZ, where the guest virtual memory isn't directly
accessible by the host with user accessors.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
-rw-r--r-- | arch/mips/include/asm/kvm_host.h | 4 | ||||
-rw-r--r-- | arch/mips/kvm/emulate.c | 48 | ||||
-rw-r--r-- | arch/mips/kvm/entry.c | 14 | ||||
-rw-r--r-- | arch/mips/kvm/mips.c | 2 |
4 files changed, 64 insertions, 4 deletions
diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h index f296ebeda9e3..17c5e53ef3fa 100644 --- a/arch/mips/include/asm/kvm_host.h +++ b/arch/mips/include/asm/kvm_host.h @@ -280,6 +280,8 @@ struct kvm_vcpu_arch { unsigned long host_cp0_badvaddr; unsigned long host_cp0_epc; u32 host_cp0_cause; + u32 host_cp0_badinstr; + u32 host_cp0_badinstrp; /* GPRS */ unsigned long gprs[32]; @@ -641,6 +643,8 @@ void kvm_trap_emul_invalidate_gva(struct kvm_vcpu *vcpu, unsigned long addr, /* Emulation */ int kvm_get_inst(u32 *opc, struct kvm_vcpu *vcpu, u32 *out); enum emulation_result update_pc(struct kvm_vcpu *vcpu, u32 cause); +int kvm_get_badinstr(u32 *opc, struct kvm_vcpu *vcpu, u32 *out); +int kvm_get_badinstrp(u32 *opc, struct kvm_vcpu *vcpu, u32 *out); /** * kvm_is_ifetch_fault() - Find whether a TLBL exception is due to ifetch fault. diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c index b906fc0589f3..b295a4a1496f 100644 --- a/arch/mips/kvm/emulate.c +++ b/arch/mips/kvm/emulate.c @@ -54,7 +54,7 @@ static int kvm_compute_return_epc(struct kvm_vcpu *vcpu, unsigned long instpc, } /* Read the instruction */ - err = kvm_get_inst((u32 *)epc, vcpu, &insn.word); + err = kvm_get_badinstrp((u32 *)epc, vcpu, &insn.word); if (err) return err; @@ -259,6 +259,48 @@ enum emulation_result update_pc(struct kvm_vcpu *vcpu, u32 cause) } /** + * kvm_get_badinstr() - Get bad instruction encoding. + * @opc: Guest pointer to faulting instruction. + * @vcpu: KVM VCPU information. + * + * Gets the instruction encoding of the faulting instruction, using the saved + * BadInstr register value if it exists, otherwise falling back to reading guest + * memory at @opc. + * + * Returns: The instruction encoding of the faulting instruction. + */ +int kvm_get_badinstr(u32 *opc, struct kvm_vcpu *vcpu, u32 *out) +{ + if (cpu_has_badinstr) { + *out = vcpu->arch.host_cp0_badinstr; + return 0; + } else { + return kvm_get_inst(opc, vcpu, out); + } +} + +/** + * kvm_get_badinstrp() - Get bad prior instruction encoding. + * @opc: Guest pointer to prior faulting instruction. + * @vcpu: KVM VCPU information. + * + * Gets the instruction encoding of the prior faulting instruction (the branch + * containing the delay slot which faulted), using the saved BadInstrP register + * value if it exists, otherwise falling back to reading guest memory at @opc. + * + * Returns: The instruction encoding of the prior faulting instruction. + */ +int kvm_get_badinstrp(u32 *opc, struct kvm_vcpu *vcpu, u32 *out) +{ + if (cpu_has_badinstrp) { + *out = vcpu->arch.host_cp0_badinstrp; + return 0; + } else { + return kvm_get_inst(opc, vcpu, out); + } +} + +/** * kvm_mips_count_disabled() - Find whether the CP0_Count timer is disabled. * @vcpu: Virtual CPU. * @@ -1839,7 +1881,7 @@ enum emulation_result kvm_mips_emulate_inst(u32 cause, u32 *opc, /* Fetch the instruction. */ if (cause & CAUSEF_BD) opc += 1; - err = kvm_get_inst(opc, vcpu, &inst.word); + err = kvm_get_badinstr(opc, vcpu, &inst.word); if (err) return EMULATE_FAIL; @@ -2434,7 +2476,7 @@ enum emulation_result kvm_mips_handle_ri(u32 cause, u32 *opc, /* Fetch the instruction. */ if (cause & CAUSEF_BD) opc += 1; - err = kvm_get_inst(opc, vcpu, &inst.word); + err = kvm_get_badinstr(opc, vcpu, &inst.word); if (err) { kvm_err("%s: Cannot get inst @ %p (%d)\n", __func__, opc, err); return EMULATE_FAIL; diff --git a/arch/mips/kvm/entry.c b/arch/mips/kvm/entry.c index 1ae33e0e675c..c5b254c4d0da 100644 --- a/arch/mips/kvm/entry.c +++ b/arch/mips/kvm/entry.c @@ -53,6 +53,8 @@ /* Some CP0 registers */ #define C0_HWRENA 7, 0 #define C0_BADVADDR 8, 0 +#define C0_BADINSTR 8, 1 +#define C0_BADINSTRP 8, 2 #define C0_ENTRYHI 10, 0 #define C0_STATUS 12, 0 #define C0_CAUSE 13, 0 @@ -579,6 +581,18 @@ void *kvm_mips_build_exit(void *addr) uasm_i_mfc0(&p, K0, C0_CAUSE); uasm_i_sw(&p, K0, offsetof(struct kvm_vcpu_arch, host_cp0_cause), K1); + if (cpu_has_badinstr) { + uasm_i_mfc0(&p, K0, C0_BADINSTR); + uasm_i_sw(&p, K0, offsetof(struct kvm_vcpu_arch, + host_cp0_badinstr), K1); + } + + if (cpu_has_badinstrp) { + uasm_i_mfc0(&p, K0, C0_BADINSTRP); + uasm_i_sw(&p, K0, offsetof(struct kvm_vcpu_arch, + host_cp0_badinstrp), K1); + } + /* Now restore the host state just enough to run the handlers */ /* Switch EBASE to the one used by Linux */ diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c index 29afd96069ef..b8f04070bf39 100644 --- a/arch/mips/kvm/mips.c +++ b/arch/mips/kvm/mips.c @@ -1471,7 +1471,7 @@ int kvm_mips_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu) if (cause & CAUSEF_BD) opc += 1; inst = 0; - kvm_get_inst(opc, vcpu, &inst); + kvm_get_badinstr(opc, vcpu, &inst); kvm_err("Exception Code: %d, not yet handled, @ PC: %p, inst: 0x%08x BadVaddr: %#lx Status: %#lx\n", exccode, opc, inst, badvaddr, kvm_read_c0_guest_status(vcpu->arch.cop0)); |