From: Thomas Gleixner <tglx@linutronix.de>
To: Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com>,
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>,
Juergen Gross <jgross@suse.com>, Deep Shah <sdeep@vmware.com>,
VMware Inc <pv-drivers@vmware.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>
Cc: Peter H 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>,
Sean Christopherson <seanjc@google.com>,
Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v10 07/11] x86/tdx: Add HLT support for TDX guest
Date: Thu, 14 Oct 2021 11:30:45 +0200 [thread overview]
Message-ID: <87lf2w6ji2.ffs@tglx> (raw)
In-Reply-To: <20211009053747.1694419-8-sathyanarayanan.kuppuswamy@linux.intel.com>
On Fri, Oct 08 2021 at 22:37, Kuppuswamy Sathyanarayanan wrote:
> +/* HLT TDVMCALL sub-function ID */
> +#define EXIT_REASON_HLT 12
arch/x86/include/uapi/asm/vmx.h:#define EXIT_REASON_HLT 12
Is there a _good_ reason why this can't be reused?
> /*
> * __tdx_module_call() - Helper function used by TDX guests to request
> * services from the TDX module (does not include VMM services).
> @@ -235,6 +238,33 @@ SYM_FUNC_START(__tdx_hypercall)
>
> movl $TDVMCALL_EXPOSE_REGS_MASK, %ecx
>
> + /*
> + * For the idle loop STI needs to be called directly before
> + * the TDCALL that enters idle (EXIT_REASON_HLT case). STI
> + * enables interrupts only one instruction later. If there
> + * are any instructions between the STI and the TDCALL for
> + * HLT then an interrupt could happen in that time, but the
> + * code would go back to sleep afterwards, which can cause
> + * longer delays.
> + *
> + * This leads to significant difference in network performance
> + * benchmarks. So add a special case for EXIT_REASON_HLT to
> + * trigger STI before TDCALL. But this change is not required
> + * for all HLT cases. So use R15 register value to identify the
> + * case which needs STI. So, if R11 is EXIT_REASON_HLT and R15
> + * is 1, then call STI before TDCALL instruction. Note that R15
> + * register is not required by TDCALL ABI when triggering the
> + * hypercall for EXIT_REASON_HLT case. So use it in software to
> + * select the STI case.
> + */
> + cmpl $EXIT_REASON_HLT, %r11d
> + jne skip_sti
> + cmpl $1, %r15d
You already have a nice define for EXIT_REASON_HLT. Please add one for this
constant as well.
> + jne skip_sti
> + /* Set R15 register to 0, it is unused in EXIT_REASON_HLT case */
> + xor %r15, %r15
> + sti
> +skip_sti:
> tdcall
> bool tdx_get_ve_info(struct ve_info *ve)
> {
> struct tdx_module_output out;
> @@ -84,8 +141,19 @@ bool tdx_get_ve_info(struct ve_info *ve)
> bool tdx_handle_virtualization_exception(struct pt_regs *regs,
> struct ve_info *ve)
> {
> - pr_warn("Unexpected #VE: %lld\n", ve->exit_reason);
> - return false;
> + switch (ve->exit_reason) {
> + case EXIT_REASON_HLT:
> + tdx_halt();
> + break;
> + default:
> + pr_warn("Unexpected #VE: %lld\n", ve->exit_reason);
> + return false;
> + }
> +
> + /* After successful #VE handling, move the IP */
> + regs->ip += ve->instr_len;
> +
> + return true;
> }
>
> void __init tdx_early_init(void)
> @@ -95,5 +163,8 @@ void __init tdx_early_init(void)
>
> setup_force_cpu_cap(X86_FEATURE_TDX_GUEST);
>
> + pv_ops.irq.safe_halt = tdx_safe_halt;
> + pv_ops.irq.halt = tdx_halt;
Colour me confused, but why do we end up in #VE with EXIT_REASON_HLT
when halt/safe_halt is paravirtualized?
There may be a valid reason. If so then this lacks a comment.
Thanks,
tglx
next prev parent reply other threads:[~2021-10-14 9:30 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-09 5:37 [PATCH v10 00/11] Add TDX Guest Support (Initial support) Kuppuswamy Sathyanarayanan
2021-10-09 5:37 ` [PATCH v10 01/11] x86/paravirt: Move halt paravirt calls under CONFIG_PARAVIRT Kuppuswamy Sathyanarayanan
2021-10-15 16:59 ` David Hildenbrand
2021-10-09 5:37 ` [PATCH v10 02/11] x86/tdx: Introduce INTEL_TDX_GUEST config option Kuppuswamy Sathyanarayanan
2021-10-11 18:19 ` Josh Poimboeuf
2021-10-11 18:38 ` Andi Kleen
2021-10-11 18:47 ` Kuppuswamy, Sathyanarayanan
2021-10-09 5:37 ` [PATCH v10 03/11] x86/cpufeatures: Add TDX Guest CPU feature Kuppuswamy Sathyanarayanan
2021-10-13 8:18 ` Borislav Petkov
2021-10-13 13:32 ` Sathyanarayanan Kuppuswamy
2021-10-13 19:42 ` Josh Poimboeuf
2021-10-13 23:19 ` Thomas Gleixner
2021-10-14 0:25 ` Josh Poimboeuf
2021-10-14 7:57 ` Borislav Petkov
[not found] ` <1a6220a5-3abd-dea1-4b2f-2acade311236@linux.intel.com>
2021-10-18 21:59 ` Borislav Petkov
2021-10-18 22:04 ` Sathyanarayanan Kuppuswamy
2021-10-13 20:44 ` Thomas Gleixner
2021-10-13 21:05 ` Sathyanarayanan Kuppuswamy
2021-10-13 21:35 ` Thomas Gleixner
2021-10-13 21:07 ` Borislav Petkov
2021-10-13 21:25 ` Thomas Gleixner
2021-10-13 21:37 ` Borislav Petkov
2021-10-13 22:28 ` Sathyanarayanan Kuppuswamy
2021-10-13 23:02 ` Thomas Gleixner
2021-10-14 17:28 ` Sathyanarayanan Kuppuswamy
2021-10-09 5:37 ` [PATCH v10 04/11] x86/tdx: Add TDX support to intel_cc_platform_has() Kuppuswamy Sathyanarayanan
2021-10-13 15:57 ` Borislav Petkov
2021-10-14 7:12 ` Thomas Gleixner
2021-10-14 17:31 ` Sathyanarayanan Kuppuswamy
2021-10-09 5:37 ` [PATCH v10 05/11] x86/tdx: Add __tdx_module_call() and __tdx_hypercall() helper functions Kuppuswamy Sathyanarayanan
2021-10-14 7:28 ` Thomas Gleixner
2021-10-15 0:19 ` Sathyanarayanan Kuppuswamy
2021-10-09 5:37 ` [PATCH v10 06/11] x86/traps: Add #VE support for TDX guest Kuppuswamy Sathyanarayanan
2021-10-14 8:30 ` Thomas Gleixner
2021-10-17 2:45 ` Sathyanarayanan Kuppuswamy
2021-10-17 3:18 ` Dave Hansen
2021-10-17 3:49 ` Sathyanarayanan Kuppuswamy
2021-10-09 5:37 ` [PATCH v10 07/11] x86/tdx: Add HLT " Kuppuswamy Sathyanarayanan
2021-10-14 9:30 ` Thomas Gleixner [this message]
2021-10-15 1:33 ` Sathyanarayanan Kuppuswamy
2021-10-15 15:03 ` Sean Christopherson
2021-10-09 5:37 ` [PATCH v10 08/11] x86/tdx: Wire up KVM hypercalls Kuppuswamy Sathyanarayanan
2021-10-14 10:21 ` Thomas Gleixner
2021-10-15 3:03 ` Sathyanarayanan Kuppuswamy
2021-10-09 5:37 ` [PATCH v10 09/11] x86/tdx: Add MSR support for TDX guest Kuppuswamy Sathyanarayanan
2021-10-09 5:37 ` [PATCH v10 10/11] x86/tdx: Don't write CSTAR MSR on Intel Kuppuswamy Sathyanarayanan
2021-10-14 10:47 ` Thomas Gleixner
2021-10-14 13:47 ` Andi Kleen
2021-10-14 14:27 ` Thomas Gleixner
2021-10-09 5:37 ` [PATCH v10 11/11] x86/tdx: Handle CPUID via #VE Kuppuswamy Sathyanarayanan
2021-10-14 12:01 ` Thomas Gleixner
2021-10-14 13:25 ` Dave Hansen
2021-10-09 7:38 ` [PATCH v10 00/11] Add TDX Guest Support (Initial support) Borislav Petkov
2021-10-09 20:56 ` Kuppuswamy, Sathyanarayanan
2021-10-11 13:03 ` Borislav Petkov
2021-10-11 16:33 ` Dave Hansen
2021-10-11 16:48 ` Dave Hansen
2021-10-11 17:04 ` Borislav Petkov
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=87lf2w6ji2.ffs@tglx \
--to=tglx@linutronix.de \
--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=jgross@suse.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--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=pv-drivers@vmware.com \
--cc=sathyanarayanan.kuppuswamy@linux.intel.com \
--cc=sdeep@vmware.com \
--cc=seanjc@google.com \
--cc=tony.luck@intel.com \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.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).