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Subject: Re: [PATCH kvmtool v2 09/22] x86/ioport: Switch to new trap handlers
To:     Andre Przywara <andre.przywara@arm.com>,
        Will Deacon <will@kernel.org>,
        Julien Thierry <julien.thierry.kdev@gmail.com>
Cc:     kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
        Marc Zyngier <maz@kernel.org>,
        Sami Mujawar <sami.mujawar@arm.com>
References: <20210225005915.26423-1-andre.przywara@arm.com>
 <20210225005915.26423-10-andre.przywara@arm.com>
From:   Alexandru Elisei <alexandru.elisei@arm.com>
Message-ID: <fb420e89-da92-2100-a12c-475152ff30d4@arm.com>
Date:   Tue, 9 Mar 2021 12:09:52 +0000
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Hi Andre,

On 2/25/21 12:59 AM, Andre Przywara wrote:
> Now that the x86 I/O ports have trap handlers adhering to the MMIO fault
> handler prototype, let's switch over to the joint registration routine.
>
> This allows us to get rid of the ioport shim routines.
>
> Since the debug output was done in ioport.c, we would lose this
> functionality when moving over to the MMIO handlers. So bring this back
> here explicitly, by introducing debug_mmio().
>
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  x86/ioport.c | 102 +++++++++++++++++++--------------------------------
>  1 file changed, 37 insertions(+), 65 deletions(-)
>
> diff --git a/x86/ioport.c b/x86/ioport.c
> index 78f9a863..9fcbb6c9 100644
> --- a/x86/ioport.c
> +++ b/x86/ioport.c
> @@ -3,21 +3,35 @@
>  #include <stdlib.h>
>  #include <stdio.h>
>  
> -static void dummy_mmio(struct kvm_cpu *vcpu, u64 addr, u8 *data, u32 len,
> +static void debug_mmio(struct kvm_cpu *vcpu, u64 addr, u8 *data, u32 len,
>  		       u8 is_write, void *ptr)

Since the function is about ioports (it even checks cfg.ioport_debug), shouldn't
something like debug_io/debug_pio/debug_ioport/<something else ioport related> be
more appropriate?

Otherwise looks good: the only emulation callback that could fail was
debug_ops->debug_io_out, which triggered a print if cfg.ioport_debug was set, and
the callback is replaced by debug_mmio. With the name change:

Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>

Thanks,

Alex

>  {
> +	if (!vcpu->kvm->cfg.ioport_debug)
> +		return;
> +
> +	fprintf(stderr, "debug port %s from VCPU%lu: port=0x%lx, size=%u",
> +		is_write ? "write" : "read", vcpu->cpu_id,
> +		(unsigned long)addr, len);
> +	if (is_write) {
> +		u32 value;
> +
> +		switch (len) {
> +		case 1: value = ioport__read8(data); break;
> +		case 2: value = ioport__read16((u16*)data); break;
> +		case 4: value = ioport__read32((u32*)data); break;
> +		default: value = 0; break;
> +		}
> +		fprintf(stderr, ", data: 0x%x\n", value);
> +	} else {
> +		fprintf(stderr, "\n");
> +	}
>  }
>  
> -static bool debug_io_out(struct ioport *ioport, struct kvm_cpu *vcpu, u16 port, void *data, int size)
> +static void dummy_mmio(struct kvm_cpu *vcpu, u64 addr, u8 *data, u32 len,
> +		       u8 is_write, void *ptr)
>  {
> -	dummy_mmio(vcpu, port, data, size, true, NULL);
> -	return 0;
>  }
>  
> -static struct ioport_operations debug_ops = {
> -	.io_out		= debug_io_out,
> -};
> -
>  static void seabios_debug_mmio(struct kvm_cpu *vcpu, u64 addr, u8 *data,
>  			       u32 len, u8 is_write, void *ptr)
>  {
> @@ -31,37 +45,6 @@ static void seabios_debug_mmio(struct kvm_cpu *vcpu, u64 addr, u8 *data,
>  	putchar(ch);
>  }
>  
> -static bool seabios_debug_io_out(struct ioport *ioport, struct kvm_cpu *vcpu, u16 port, void *data, int size)
> -{
> -	seabios_debug_mmio(vcpu, port, data, size, true, NULL);
> -	return 0;
> -}
> -
> -static struct ioport_operations seabios_debug_ops = {
> -	.io_out		= seabios_debug_io_out,
> -};
> -
> -static bool dummy_io_in(struct ioport *ioport, struct kvm_cpu *vcpu, u16 port, void *data, int size)
> -{
> -	dummy_mmio(vcpu, port, data, size, false, NULL);
> -	return true;
> -}
> -
> -static bool dummy_io_out(struct ioport *ioport, struct kvm_cpu *vcpu, u16 port, void *data, int size)
> -{
> -	dummy_mmio(vcpu, port, data, size, true, NULL);
> -	return true;
> -}
> -
> -static struct ioport_operations dummy_read_write_ioport_ops = {
> -	.io_in		= dummy_io_in,
> -	.io_out		= dummy_io_out,
> -};
> -
> -static struct ioport_operations dummy_write_only_ioport_ops = {
> -	.io_out		= dummy_io_out,
> -};
> -
>  /*
>   * The "fast A20 gate"
>   */
> @@ -76,17 +59,6 @@ static void ps2_control_mmio(struct kvm_cpu *vcpu, u64 addr, u8 *data, u32 len,
>  		ioport__write8(data, 0x02);
>  }
>  
> -static bool ps2_control_a_io_in(struct ioport *ioport, struct kvm_cpu *vcpu, u16 port, void *data, int size)
> -{
> -	ps2_control_mmio(vcpu, port, data, size, false, NULL);
> -	return true;
> -}
> -
> -static struct ioport_operations ps2_control_a_ops = {
> -	.io_in		= ps2_control_a_io_in,
> -	.io_out		= dummy_io_out,
> -};
> -
>  void ioport__map_irq(u8 *irq)
>  {
>  }
> @@ -98,75 +70,75 @@ static int ioport__setup_arch(struct kvm *kvm)
>  	/* Legacy ioport setup */
>  
>  	/* 0000 - 001F - DMA1 controller */
> -	r = ioport__register(kvm, 0x0000, &dummy_read_write_ioport_ops, 32, NULL);
> +	r = kvm__register_pio(kvm, 0x0000, 32, dummy_mmio, NULL);
>  	if (r < 0)
>  		return r;
>  
>  	/* 0x0020 - 0x003F - 8259A PIC 1 */
> -	r = ioport__register(kvm, 0x0020, &dummy_read_write_ioport_ops, 2, NULL);
> +	r = kvm__register_pio(kvm, 0x0020, 2, dummy_mmio, NULL);
>  	if (r < 0)
>  		return r;
>  
>  	/* PORT 0040-005F - PIT - PROGRAMMABLE INTERVAL TIMER (8253, 8254) */
> -	r = ioport__register(kvm, 0x0040, &dummy_read_write_ioport_ops, 4, NULL);
> +	r = kvm__register_pio(kvm, 0x0040, 4, dummy_mmio, NULL);
>  	if (r < 0)
>  		return r;
>  
>  	/* 0092 - PS/2 system control port A */
> -	r = ioport__register(kvm, 0x0092, &ps2_control_a_ops, 1, NULL);
> +	r = kvm__register_pio(kvm, 0x0092, 1, ps2_control_mmio, NULL);
>  	if (r < 0)
>  		return r;
>  
>  	/* 0x00A0 - 0x00AF - 8259A PIC 2 */
> -	r = ioport__register(kvm, 0x00A0, &dummy_read_write_ioport_ops, 2, NULL);
> +	r = kvm__register_pio(kvm, 0x00A0, 2, dummy_mmio, NULL);
>  	if (r < 0)
>  		return r;
>  
>  	/* 00C0 - 001F - DMA2 controller */
> -	r = ioport__register(kvm, 0x00C0, &dummy_read_write_ioport_ops, 32, NULL);
> +	r = kvm__register_pio(kvm, 0x00c0, 32, dummy_mmio, NULL);
>  	if (r < 0)
>  		return r;
>  
>  	/* PORT 00E0-00EF are 'motherboard specific' so we use them for our
>  	   internal debugging purposes.  */
> -	r = ioport__register(kvm, IOPORT_DBG, &debug_ops, 1, NULL);
> +	r = kvm__register_pio(kvm, IOPORT_DBG, 1, debug_mmio, NULL);
>  	if (r < 0)
>  		return r;
>  
>  	/* PORT 00ED - DUMMY PORT FOR DELAY??? */
> -	r = ioport__register(kvm, 0x00ED, &dummy_write_only_ioport_ops, 1, NULL);
> +	r = kvm__register_pio(kvm, 0x00ed, 1, dummy_mmio, NULL);
>  	if (r < 0)
>  		return r;
>  
>  	/* 0x00F0 - 0x00FF - Math co-processor */
> -	r = ioport__register(kvm, 0x00F0, &dummy_write_only_ioport_ops, 2, NULL);
> +	r = kvm__register_pio(kvm, 0x00f0, 2, dummy_mmio, NULL);
>  	if (r < 0)
>  		return r;
>  
>  	/* PORT 0278-027A - PARALLEL PRINTER PORT (usually LPT1, sometimes LPT2) */
> -	r = ioport__register(kvm, 0x0278, &dummy_read_write_ioport_ops, 3, NULL);
> +	r = kvm__register_pio(kvm, 0x0278, 3, dummy_mmio, NULL);
>  	if (r < 0)
>  		return r;
>  
>  	/* PORT 0378-037A - PARALLEL PRINTER PORT (usually LPT2, sometimes LPT3) */
> -	r = ioport__register(kvm, 0x0378, &dummy_read_write_ioport_ops, 3, NULL);
> +	r = kvm__register_pio(kvm, 0x0378, 3, dummy_mmio, NULL);
>  	if (r < 0)
>  		return r;
>  
>  	/* PORT 03D4-03D5 - COLOR VIDEO - CRT CONTROL REGISTERS */
> -	r = ioport__register(kvm, 0x03D4, &dummy_read_write_ioport_ops, 1, NULL);
> +	r = kvm__register_pio(kvm, 0x03d4, 1, dummy_mmio, NULL);
>  	if (r < 0)
>  		return r;
> -	r = ioport__register(kvm, 0x03D5, &dummy_write_only_ioport_ops, 1, NULL);
> +	r = kvm__register_pio(kvm, 0x03d5, 1, dummy_mmio, NULL);
>  	if (r < 0)
>  		return r;
>  
> -	r = ioport__register(kvm, 0x402, &seabios_debug_ops, 1, NULL);
> +	r = kvm__register_pio(kvm, 0x0402, 1, seabios_debug_mmio, NULL);
>  	if (r < 0)
>  		return r;
>  
>  	/* 0510 - QEMU BIOS configuration register */
> -	r = ioport__register(kvm, 0x510, &dummy_read_write_ioport_ops, 2, NULL);
> +	r = kvm__register_pio(kvm, 0x0510, 2, dummy_mmio, NULL);
>  	if (r < 0)
>  		return r;
>