From: Sean Christopherson <seanjc@google.com>
To: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
David Hildenbrand <david@redhat.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
"H . Peter Anvin" <hpa@zytor.com>,
Dave Hansen <dave.hansen@intel.com>,
Tony Luck <tony.luck@intel.com>,
Dan Williams <dan.j.williams@intel.com>,
Andi Kleen <ak@linux.intel.com>,
Kirill Shutemov <kirill.shutemov@linux.intel.com>,
Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v7 05/10] x86/tdx: Handle port I/O
Date: Fri, 5 Nov 2021 21:23:55 +0000 [thread overview]
Message-ID: <YYWg6wa398Vw6FJu@google.com> (raw)
In-Reply-To: <20211005204136.1812078-6-sathyanarayanan.kuppuswamy@linux.intel.com>
On Tue, Oct 05, 2021, Kuppuswamy Sathyanarayanan wrote:
> diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c
> index 4cbffcb737d9..cd0fb5d14ad7 100644
> --- a/arch/x86/kernel/tdx.c
> +++ b/arch/x86/kernel/tdx.c
> @@ -175,6 +175,38 @@ static u64 tdx_handle_cpuid(struct pt_regs *regs)
> return ret;
> }
>
> +/*
> + * tdx_handle_early_io() cannot be re-used in #VE handler for handling
> + * I/O because the way of handling string I/O is different between
> + * normal and early I/O case. Also, once trace support is enabled,
> + * tdx_handle_io() will be extended to use trace calls which is also
> + * not valid for early I/O cases.
> + */
> +static void tdx_handle_io(struct pt_regs *regs, u32 exit_qual)
> +{
> + struct tdx_hypercall_output outh;
Same comments as patch 04.
> + int out, size, port, ret;
> + bool string;
> + u64 mask;
> +
> + string = VE_IS_IO_STRING(exit_qual);
> +
> + /* I/O strings ops are unrolled at build time. */
> + BUG_ON(string);
And here as well.
> +
> + out = VE_IS_IO_OUT(exit_qual);
> + size = VE_GET_IO_SIZE(exit_qual);
> + port = VE_GET_PORT_NUM(exit_qual);
> + mask = GENMASK(8 * size, 0);
And here.
> +
> + ret = _tdx_hypercall(EXIT_REASON_IO_INSTRUCTION, size, out, port,
> + regs->ax, &outh);
This one too.
> + if (!out) {
This needs to check "ret". In general, why is this continuing on if I/O fails?
If I/O fails, the kernel done messed up and some downstream driver is going to
be real unhappy. At a minimum, it should WARN.
On a related topic, the GHCB says:
TDG.VP.VMCALL_INVALID_OPERAND 0x80000000 00000000 Invalid-IO-Port access
The "Invalid-IO-Port access" in particular is poorly worded as it implies the VMM
is allowed to deny access to ports, but AFAIK that's not the intention. A better
phrasing would be something like "Reserved value in input GPR".
The GHCI should probably also state that bits 63:16 of R14 (port) are reserved.
> + regs->ax &= ~mask;
> + regs->ax |= (ret ? UINT_MAX : outh.r11) & mask;
> + }
> +}
next prev parent reply other threads:[~2021-11-05 21:24 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-05 20:41 [PATCH v7 00/10] Add TDX Guest Support (#VE handler support) Kuppuswamy Sathyanarayanan
2021-10-05 20:41 ` [PATCH v7 01/10] x86/io: Allow to override inX() and outX() implementation Kuppuswamy Sathyanarayanan
2021-10-17 19:27 ` Thomas Gleixner
2021-10-17 20:17 ` Sathyanarayanan Kuppuswamy
2021-10-05 20:41 ` [PATCH v7 02/10] x86/tdx: Add early_is_tdx_guest() interface Kuppuswamy Sathyanarayanan
2021-10-17 19:28 ` Thomas Gleixner
2021-10-05 20:41 ` [PATCH v7 03/10] x86/tdx: Handle port I/O in decompression code Kuppuswamy Sathyanarayanan
2021-10-05 20:41 ` [PATCH v7 04/10] x86/tdx: Handle early IO operations Kuppuswamy Sathyanarayanan
2021-11-05 21:12 ` Sean Christopherson
2021-11-05 23:08 ` Sathyanarayanan Kuppuswamy
2021-10-05 20:41 ` [PATCH v7 05/10] x86/tdx: Handle port I/O Kuppuswamy Sathyanarayanan
2021-10-17 19:58 ` Thomas Gleixner
2021-10-17 20:35 ` Sathyanarayanan Kuppuswamy
2021-10-18 13:52 ` Tom Lendacky
2021-10-18 18:42 ` Sathyanarayanan Kuppuswamy
2021-11-05 21:23 ` Sean Christopherson [this message]
2021-10-05 20:41 ` [PATCH v7 06/10] x86/insn-eval: Introduce insn_get_modrm_reg_ptr() Kuppuswamy Sathyanarayanan
2021-10-05 20:41 ` [PATCH v7 07/10] x86/insn-eval: Introduce insn_decode_mmio() Kuppuswamy Sathyanarayanan
2021-10-05 20:41 ` [PATCH v7 08/10] x86/sev-es: Use insn_decode_mmio() for MMIO implementation Kuppuswamy Sathyanarayanan
2021-10-05 20:41 ` [PATCH v7 09/10] x86/tdx: Handle in-kernel MMIO Kuppuswamy Sathyanarayanan
2021-11-05 22:41 ` Sean Christopherson
2021-10-05 20:41 ` [PATCH v7 10/10] x86/tdx: Handle MWAIT and MONITOR Kuppuswamy Sathyanarayanan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YYWg6wa398Vw6FJu@google.com \
--to=seanjc@google.com \
--cc=aarcange@redhat.com \
--cc=ak@linux.intel.com \
--cc=bp@alien8.de \
--cc=dan.j.williams@intel.com \
--cc=dave.hansen@intel.com \
--cc=david@redhat.com \
--cc=hpa@zytor.com \
--cc=jpoimboe@redhat.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=knsathya@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=pbonzini@redhat.com \
--cc=sathyanarayanan.kuppuswamy@linux.intel.com \
--cc=tglx@linutronix.de \
--cc=tony.luck@intel.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).