From: Ralf Ramsauer <ralf.ramsauer@oth-regensburg.de>
To: Borislav Petkov <bp@alien8.de>
Cc: Jan Kiszka <jan.kiszka@siemens.com>, <x86@kernel.org>,
<jailhouse-dev@googlegroups.com>, <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v5 2/2] x86/jailhouse: Only enable platform UARTs if available
Date: Mon, 7 Oct 2019 18:44:39 +0200 [thread overview]
Message-ID: <85502467-d13b-084e-cdb8-d891178e97d8@oth-regensburg.de> (raw)
In-Reply-To: <20191007162636.GD24289@zn.tnic>
On 10/7/19 6:26 PM, Borislav Petkov wrote:
> On Mon, Oct 07, 2019 at 02:38:19PM +0200, Ralf Ramsauer wrote:
>> ACPI tables aren't available if Linux runs as guest of the hypervisor
>> Jailhouse. This makes the 8250 driver probe for all platform UARTs as
>> it assumes that all platform are present in case of !ACPI. Jailhouse
>
> I think you mean s/platform/UARTs/ here.
>
>> will stop execution of Linux guest due to port access violation.
>>
>> So far, these access violations could be solved by tuning the
>> 8250.nr_uarts parameter but it has limitations: We can, e.g., only map
>
> Another "We" you can get rid of.
>
>> consecutive platform UARTs to Linux, and only in the sequence 0x3f8,
>> 0x2f8, 0x3e8, 0x2e8.
>>
>> Beginning from setup_data version 2, Jailhouse will place information of
>> available platform UARTs in setup_data. This allows for selective
>> activation of platform UARTs.
>>
>> This patch queries the setup_data version and activates only available
>
> s/This patch queries/Query/
>
>> UARTS. It comes with backward compatibility, and will still support
>> older setup_data versions. In this case, Linux falls back to the old
>> behaviour.
>>
>> Signed-off-by: Ralf Ramsauer <ralf.ramsauer@oth-regensburg.de>
>> ---
>> arch/x86/include/uapi/asm/bootparam.h | 3 +
>> arch/x86/kernel/jailhouse.c | 83 +++++++++++++++++++++++----
>> 2 files changed, 74 insertions(+), 12 deletions(-)
>
> ...
>
>> @@ -138,6 +147,53 @@ static int __init jailhouse_pci_arch_init(void)
>> return 0;
>> }
>>
>> +#ifdef CONFIG_SERIAL_8250
>> +static bool jailhouse_uart_enabled(unsigned int uart_nr)
>> +{
>> + return setup_data.v2.flags & BIT(uart_nr);
>> +}
>> +
>> +static void jailhouse_serial_fixup(int port, struct uart_port *up,
>> + u32 *capabilities)
>> +{
>> + static const u16 pcuart_base[] = {0x3f8, 0x2f8, 0x3e8, 0x2e8};
>> + unsigned int n;
>> +
>> + for (n = 0; n < ARRAY_SIZE(pcuart_base); n++) {
>> + if (pcuart_base[n] != up->iobase)
>> + continue;
>> +
>> + if (jailhouse_uart_enabled(n)) {
>> + pr_info("Enabling UART%u (port 0x%lx)\n", n,
>> + up->iobase);
>> + jailhouse_setup_irq(up->irq);
>> + } else {
>> + /* Deactivate UART if access isn't allowed */
>> + up->iobase = 0;
>> + }
>> + break;
>> + }
>> +}
>
> WARNING: vmlinux.o(.text+0x4fdb0): Section mismatch in reference from the function jailhouse_serial_fixup() to the variable .init.data:can_use_brk_pgt
> The function jailhouse_serial_fixup() references
> the variable __initdata can_use_brk_pgt.
> This is often because jailhouse_serial_fixup lacks a __initdata
> annotation or the annotation of can_use_brk_pgt is wrong.
>
Yep, jailhouse_serial_fixup can become __init, I didn't see that, but
you're right, thanks. I'm curious, how did you find that? "We" didn't
notice yet. :-)
BTW, we refers to the Jailhouse folks, but I will rewrite that.
Thanks
Ralf
next prev parent reply other threads:[~2019-10-07 16:44 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-07 12:38 [PATCH v5 0/2] x86/jailhouse: improve probing of platform UARTs Ralf Ramsauer
2019-10-07 12:38 ` [PATCH v5 1/2] x86/jailhouse: improve setup data version comparison Ralf Ramsauer
2019-10-07 16:25 ` Borislav Petkov
2019-10-07 18:25 ` [tip: x86/platform] x86/jailhouse: Improve " tip-bot2 for Ralf Ramsauer
2019-10-07 12:38 ` [PATCH v5 2/2] x86/jailhouse: Only enable platform UARTs if available Ralf Ramsauer
2019-10-07 15:20 ` Jan Kiszka
2019-10-07 16:26 ` Borislav Petkov
2019-10-07 16:44 ` Ralf Ramsauer [this message]
2019-10-07 16:59 ` Borislav Petkov
2019-10-07 18:25 ` [tip: x86/platform] x86/jailhouse: Enable platform UARTs only " tip-bot2 for Ralf Ramsauer
2019-10-07 18:27 ` Ingo Molnar
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