From: Maxim Levitsky <mlevitsk@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: seanjc@google.com
Subject: Re: [PATCH 08/13] KVM: x86: inline kernel_pio into its sole caller
Date: Tue, 26 Oct 2021 16:55:59 +0300 [thread overview]
Message-ID: <e43a66f1cc08ad185f044ece8ada5c64da2b40eb.camel@redhat.com> (raw)
In-Reply-To: <20211022153616.1722429-9-pbonzini@redhat.com>
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
next prev parent reply other threads:[~2021-10-26 13:56 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-22 15:36 [PATCH v2 00/13] fixes and cleanups for string I/O emulation Paolo Bonzini
2021-10-22 15:36 ` [PATCH 01/13] KVM: SEV-ES: rename guest_ins_data to sev_pio_data Paolo Bonzini
2021-10-22 15:36 ` [PATCH 02/13] KVM: x86: leave vcpu->arch.pio.count alone in emulator_pio_in_out Paolo Bonzini
2021-10-22 15:36 ` [PATCH 03/13] KVM: SEV-ES: clean up kvm_sev_es_ins/outs Paolo Bonzini
2021-10-22 15:36 ` [PATCH 04/13] KVM: x86: split the two parts of emulator_pio_in Paolo Bonzini
2021-10-22 15:36 ` [PATCH 05/13] KVM: x86: remove unnecessary arguments from complete_emulator_pio_in Paolo Bonzini
2021-10-22 15:36 ` [PATCH 06/13] KVM: SEV-ES: keep INS functions together Paolo Bonzini
2021-10-22 15:36 ` [PATCH 07/13] KVM: SEV-ES: go over the sev_pio_data buffer in multiple passes if needed Paolo Bonzini
2021-10-22 15:36 ` [PATCH 08/13] KVM: x86: inline kernel_pio into its sole caller Paolo Bonzini
2021-10-26 13:55 ` Maxim Levitsky [this message]
2021-10-22 15:36 ` [PATCH 09/13] KVM: x86: move all vcpu->arch.pio* setup in emulator_pio_in_out Paolo Bonzini
2021-10-26 13:56 ` Maxim Levitsky
2021-10-22 15:36 ` [PATCH 10/13] KVM: x86: wean in-kernel PIO from vcpu->arch.pio* Paolo Bonzini
2021-10-26 13:56 ` Maxim Levitsky
2021-10-22 15:36 ` [PATCH 11/13] KVM: x86: wean fast IN from emulator_pio_in Paolo Bonzini
2021-10-26 13:56 ` Maxim Levitsky
2021-10-22 15:36 ` [PATCH 12/13] KVM: x86: de-underscorify __emulator_pio_in Paolo Bonzini
2021-10-26 13:56 ` Maxim Levitsky
2021-10-22 15:36 ` [PATCH 13/13] KVM: SEV-ES: reuse advance_sev_es_emulated_ins for OUT too Paolo Bonzini
2021-10-26 13:57 ` Maxim Levitsky
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