| Message ID | 20211022153616.1722429-9-pbonzini@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fixes and cleanups for string I/O emulation | expand |
On Fri, 2021-10-22 at 11:36 -0400, Paolo Bonzini wrote: > The caller of kernel_pio already has arguments for most of what kernel_pio > fishes out of vcpu->arch.pio. This is the first step towards ensuring that > vcpu->arch.pio.* is only used when exiting to userspace. > > We can now also WARN if emulated PIO performs successful in-kernel iterations > before having to fall back to userspace. The code is not ready for that, and > it should never happen. > > No functional change intended. > > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > arch/x86/kvm/x86.c | 39 +++++++++++++++++---------------------- > 1 file changed, 17 insertions(+), 22 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index b26647a5ea22..d6b8df7cea80 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -6886,37 +6886,32 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt, > return emulator_write_emulated(ctxt, addr, new, bytes, exception); > } > > -static int kernel_pio(struct kvm_vcpu *vcpu, void *pd) > -{ > - int r = 0, i; > - > - for (i = 0; i < vcpu->arch.pio.count; i++) { > - if (vcpu->arch.pio.in) > - r = kvm_io_bus_read(vcpu, KVM_PIO_BUS, vcpu->arch.pio.port, > - vcpu->arch.pio.size, pd); > - else > - r = kvm_io_bus_write(vcpu, KVM_PIO_BUS, > - vcpu->arch.pio.port, vcpu->arch.pio.size, > - pd); > - if (r) > - break; > - pd += vcpu->arch.pio.size; > - } > - return r; > -} > - > static int emulator_pio_in_out(struct kvm_vcpu *vcpu, int size, > unsigned short port, > unsigned int count, bool in) > { > + void *data = vcpu->arch.pio_data; > + unsigned i; > + int r; > + > vcpu->arch.pio.port = port; > vcpu->arch.pio.in = in; > - vcpu->arch.pio.count = count; > + vcpu->arch.pio.count = count; > vcpu->arch.pio.size = size; > > - if (!kernel_pio(vcpu, vcpu->arch.pio_data)) > - return 1; > + for (i = 0; i < count; i++) { > + if (in) > + r = kvm_io_bus_read(vcpu, KVM_PIO_BUS, port, size, data); > + else > + r = kvm_io_bus_write(vcpu, KVM_PIO_BUS, port, size, data); > + if (r) > + goto userspace_io; > + data += size; > + } > + return 1; > > +userspace_io: > + WARN_ON(i != 0); > vcpu->run->exit_reason = KVM_EXIT_IO; > vcpu->run->io.direction = in ? KVM_EXIT_IO_IN : KVM_EXIT_IO_OUT; > vcpu->run->io.size = size; Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Best regards, Maxim Levitsky
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b26647a5ea22..d6b8df7cea80 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6886,37 +6886,32 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt, return emulator_write_emulated(ctxt, addr, new, bytes, exception); } -static int kernel_pio(struct kvm_vcpu *vcpu, void *pd) -{ - int r = 0, i; - - for (i = 0; i < vcpu->arch.pio.count; i++) { - if (vcpu->arch.pio.in) - r = kvm_io_bus_read(vcpu, KVM_PIO_BUS, vcpu->arch.pio.port, - vcpu->arch.pio.size, pd); - else - r = kvm_io_bus_write(vcpu, KVM_PIO_BUS, - vcpu->arch.pio.port, vcpu->arch.pio.size, - pd); - if (r) - break; - pd += vcpu->arch.pio.size; - } - return r; -} - static int emulator_pio_in_out(struct kvm_vcpu *vcpu, int size, unsigned short port, unsigned int count, bool in) { + void *data = vcpu->arch.pio_data; + unsigned i; + int r; + vcpu->arch.pio.port = port; vcpu->arch.pio.in = in; - vcpu->arch.pio.count = count; + vcpu->arch.pio.count = count; vcpu->arch.pio.size = size; - if (!kernel_pio(vcpu, vcpu->arch.pio_data)) - return 1; + for (i = 0; i < count; i++) { + if (in) + r = kvm_io_bus_read(vcpu, KVM_PIO_BUS, port, size, data); + else + r = kvm_io_bus_write(vcpu, KVM_PIO_BUS, port, size, data); + if (r) + goto userspace_io; + data += size; + } + return 1; +userspace_io: + WARN_ON(i != 0); vcpu->run->exit_reason = KVM_EXIT_IO; vcpu->run->io.direction = in ? KVM_EXIT_IO_IN : KVM_EXIT_IO_OUT; vcpu->run->io.size = size;
The caller of kernel_pio already has arguments for most of what kernel_pio fishes out of vcpu->arch.pio. This is the first step towards ensuring that vcpu->arch.pio.* is only used when exiting to userspace. We can now also WARN if emulated PIO performs successful in-kernel iterations before having to fall back to userspace. The code is not ready for that, and it should never happen. No functional change intended. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- arch/x86/kvm/x86.c | 39 +++++++++++++++++---------------------- 1 file changed, 17 insertions(+), 22 deletions(-)