[RFC PATCH v1 02/28] kvm: svm: Add kvm_fast_pio_in support
From: Brijesh Singh <hidden>
Date: 2016-08-22 23:57:09
Also in:
kvm, linux-efi, lkml
Subsystem:
kernel virtual machine for x86 (kvm/x86), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Sean Christopherson, Paolo Bonzini, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: Tom Lendacky <thomas.lendacky@amd.com> Update the I/O interception support to add the kvm_fast_pio_in function to speed up the in instruction similar to the out instruction. Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/svm.c | 5 +++-- arch/x86/kvm/x86.c | 43 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 47 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 3f05d36..c38f878 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h@@ -1133,6 +1133,7 @@ int kvm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr); struct x86_emulate_ctxt; int kvm_fast_pio_out(struct kvm_vcpu *vcpu, int size, unsigned short port); +int kvm_fast_pio_in(struct kvm_vcpu *vcpu, int size, unsigned short port); void kvm_emulate_cpuid(struct kvm_vcpu *vcpu); int kvm_emulate_halt(struct kvm_vcpu *vcpu); int kvm_vcpu_halt(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index d8b9c8c..fd5a9a8 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c@@ -2131,7 +2131,7 @@ static int io_interception(struct vcpu_svm *svm) ++svm->vcpu.stat.io_exits; string = (io_info & SVM_IOIO_STR_MASK) != 0; in = (io_info & SVM_IOIO_TYPE_MASK) != 0; - if (string || in) + if (string) return emulate_instruction(vcpu, 0) == EMULATE_DONE; port = io_info >> 16;
@@ -2139,7 +2139,8 @@ static int io_interception(struct vcpu_svm *svm) svm->next_rip = svm->vmcb->control.exit_info_2; skip_emulated_instruction(&svm->vcpu); - return kvm_fast_pio_out(vcpu, size, port); + return in ? kvm_fast_pio_in(vcpu, size, port) + : kvm_fast_pio_out(vcpu, size, port); } static int nmi_interception(struct vcpu_svm *svm)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d432894..78295b0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c@@ -5579,6 +5579,49 @@ int kvm_fast_pio_out(struct kvm_vcpu *vcpu, int size, unsigned short port) } EXPORT_SYMBOL_GPL(kvm_fast_pio_out); +static int complete_fast_pio_in(struct kvm_vcpu *vcpu) +{ + unsigned long val; + + /* We should only ever be called with arch.pio.count equal to 1 */ + BUG_ON(vcpu->arch.pio.count != 1); + + /* For size less than 4 we merge, else we zero extend */ + val = (vcpu->arch.pio.size < 4) ? kvm_register_read(vcpu, VCPU_REGS_RAX) + : 0; + + /* + * Since vcpu->arch.pio.count == 1 let emulator_pio_in_emulated perform + * the copy and tracing + */ + emulator_pio_in_emulated(&vcpu->arch.emulate_ctxt, vcpu->arch.pio.size, + vcpu->arch.pio.port, &val, 1); + kvm_register_write(vcpu, VCPU_REGS_RAX, val); + + return 1; +} + +int kvm_fast_pio_in(struct kvm_vcpu *vcpu, int size, unsigned short port) +{ + unsigned long val; + int ret; + + /* For size less than 4 we merge, else we zero extend */ + val = (size < 4) ? kvm_register_read(vcpu, VCPU_REGS_RAX) : 0; + + ret = emulator_pio_in_emulated(&vcpu->arch.emulate_ctxt, size, port, + &val, 1); + if (ret) { + kvm_register_write(vcpu, VCPU_REGS_RAX, val); + return ret; + } + + vcpu->arch.complete_userspace_io = complete_fast_pio_in; + + return 0; +} +EXPORT_SYMBOL_GPL(kvm_fast_pio_in); + static int kvmclock_cpu_down_prep(unsigned int cpu) { __this_cpu_write(cpu_tsc_khz, 0); --
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