Until this patch we bounced between the VM and the VMM for a couple of instructions after CLGI, only to find out that yet another SVM instruction follows. Since roundtrips are really expensive, it's a lot faster to emulate these few instructions. Now we can execute CLGI/VMLOAD/VMRUN on one intercept and VMEXIT/VMSAVE on another. This is a major speed improvement!
(introduced in v6, optional) Signed-off-by: Alexander Graf <[EMAIL PROTECTED]> --- arch/x86/kvm/svm.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 69 insertions(+), 0 deletions(-) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 83332d7..e246104 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -79,6 +79,11 @@ static int nested_svm_vmsave(struct vcpu_svm *svm, void *nested_vmcb, void *arg2, void *opaque); static int nested_svm_check_exception(struct vcpu_svm *svm, unsigned nr, bool has_error_code, u32 error_code); +static int vmload_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run); +static int vmsave_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run); +static int vmrun_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run); +static int stgi_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run); + static inline struct vcpu_svm *to_svm(struct kvm_vcpu *vcpu) { @@ -1456,6 +1461,50 @@ static int nested_svm_exit_handled(struct vcpu_svm *svm, bool kvm_override) nested_svm_exit_handled_real); } +static int nested_svm_emulate(struct vcpu_svm *svm, struct kvm_run *kvm_run) +{ + int er; + u32 opcode = 0; + unsigned long rip; + unsigned long rip_linear; + + svm->vmcb->save.rax = svm->vcpu.arch.regs[VCPU_REGS_RAX]; + svm->vmcb->save.rsp = svm->vcpu.arch.regs[VCPU_REGS_RSP]; + svm->vmcb->save.rip = svm->vcpu.arch.regs[VCPU_REGS_RIP]; + rip = svm->vcpu.arch.regs[VCPU_REGS_RIP]; + rip_linear = rip + svm_seg(&svm->vcpu, VCPU_SREG_CS)->base; + + er = emulator_read_std(rip_linear, (void *)&opcode, 3, &svm->vcpu); + if (er != X86EMUL_CONTINUE) + return er; + er = EMULATE_FAIL; + + switch (opcode) { + case 0xda010f: + vmload_interception(svm, kvm_run); + er = EMULATE_DONE; + break; + case 0xd8010f: + vmrun_interception(svm, kvm_run); + er = EMULATE_DONE; + break; + case 0xdb010f: + vmsave_interception(svm, kvm_run); + er = EMULATE_DONE; + break; + case 0xdc010f: + stgi_interception(svm, kvm_run); + er = EMULATE_DONE; + break; + default: + nsvm_printk("NSVM: Opcode %x unknown\n", opcode); + } + + nsvm_printk("NSVM: svm emul at 0x%lx -> %d\n", rip, er); + + return er; +} + static int nested_svm_vmexit_real(struct vcpu_svm *svm, void *arg1, void *arg2, void *opaque) { @@ -1551,6 +1600,9 @@ static int nested_svm_vmexit(struct vcpu_svm *svm) kvm_mmu_reset_context(&svm->vcpu); kvm_mmu_load(&svm->vcpu); + /* KVM calls vmsave after vmrun, so let's run it now if we can */ + nested_svm_emulate(svm, NULL); + return 0; } @@ -1773,6 +1825,23 @@ static int clgi_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run) svm_clear_vintr(svm); svm->vmcb->control.int_ctl &= ~V_IRQ_MASK; + /* Let's try to emulate as many instructions as possible in GIF=0 */ + + while(true) { + int er; + + er = emulate_instruction(&svm->vcpu, kvm_run, 0, 0, 0); + nsvm_printk("NSVM: emulating at 0x%lx -> %d\n", svm->vcpu.arch.regs[VCPU_REGS_RIP], er); + + /* So we can now emulate the SVM instructions that most probably + occur at the end of the codepath */ + if (er != EMULATE_DONE) { + while (true) + if (nested_svm_emulate(svm, kvm_run) == EMULATE_FAIL) + break; + break; + } + } return 1; } -- 1.5.6 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html