From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: "Nikunj A. Dadhania" <nikunj@amd.com>,
seanjc@google.com, pbonzini@redhat.com
Cc: Dave Hansen <dave.hansen@intel.com>,
linux-kernel@vger.kernel.org, thomas.lendacky@amd.com,
x86@kernel.org, kvm@vger.kernel.org, bp@alien8.de,
mingo@redhat.com, tglx@linutronix.de,
dave.hansen@linux.intel.com, dionnaglaze@google.com,
pgonda@google.com
Subject: Re: [PATCH v5 13/14] x86/tsc: Mark Secure TSC as reliable clocksource
Date: Thu, 2 Nov 2023 15:38:51 +0300 [thread overview]
Message-ID: <20231102123851.jsdolkfz7sd3jys7@box> (raw)
In-Reply-To: <cf92b26e-d940-4dc8-a339-56903952cee2@amd.com>
On Thu, Nov 02, 2023 at 05:46:26PM +0530, Nikunj A. Dadhania wrote:
> On 11/2/2023 5:37 PM, Nikunj A. Dadhania wrote:
> > On 11/2/2023 4:03 PM, Kirill A. Shutemov wrote:
> >> On Thu, Nov 02, 2023 at 11:23:34AM +0530, Nikunj A. Dadhania wrote:
> >>> On 10/30/2023 10:48 PM, Dave Hansen wrote:
> >>>> On 10/29/23 23:36, Nikunj A Dadhania wrote:
> >>>> ...
> >>>>> diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
> >>>>> index 15f97c0abc9d..b0a8546d3703 100644
> >>>>> --- a/arch/x86/kernel/tsc.c
> >>>>> +++ b/arch/x86/kernel/tsc.c
> >>>>> @@ -1241,7 +1241,7 @@ static void __init check_system_tsc_reliable(void)
> >>>>> tsc_clocksource_reliable = 1;
> >>>>> }
> >>>>> #endif
> >>>>> - if (boot_cpu_has(X86_FEATURE_TSC_RELIABLE))
> >>>>> + if (boot_cpu_has(X86_FEATURE_TSC_RELIABLE) || cc_platform_has(CC_ATTR_GUEST_SECURE_TSC))
> >>>>> tsc_clocksource_reliable = 1;
> >>>>
> >>>> Why can't you just set X86_FEATURE_TSC_RELIABLE?
> >>>
> >>> Last time when I tried, I had removed my kvmclock changes and I had set
> >>> the X86_FEATURE_TSC_RELIABLE similar to Kirill's patch[1], this did not
> >>> select the SecureTSC.
> >>>
> >>> Let me try setting X86_FEATURE_TSC_RELIABLE and retaining my patch for
> >>> skipping kvmclock.
> >>
> >> kvmclock lowers its rating if TSC is good enough:
> >>
> >> if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) &&
> >> boot_cpu_has(X86_FEATURE_NONSTOP_TSC) &&
> >> !check_tsc_unstable())
> >> kvm_clock.rating = 299;
> >>
> >> Does your TSC meet the requirements?
> >
> > I have set TscInvariant (bit 8) in CPUID_8000_0007_edx and TSC is set as reliable.
> >
> > With this I see kvm_clock rating being lowered, but kvm-clock is still being picked as clock-source.
>
> Ah.. at later point TSC is picked up, is this expected ?
>
> [ 2.564052] clocksource: Switched to clocksource kvm-clock
> [ 2.678136] clocksource: Switched to clocksource tsc
On bare metal I see switch from tsc-early to tsc. tsc-early rating is
equal to kvmclock rating after it gets lowered.
Maybe kvmclock rating has to be even lower after detecting sane TSC?
Sean, Paolo, any comments?
--
Kiryl Shutsemau / Kirill A. Shutemov
next prev parent reply other threads:[~2023-11-02 12:39 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-30 6:36 [PATCH v5 00/14] Add Secure TSC support for SNP guests Nikunj A Dadhania
2023-10-30 6:36 ` [PATCH v5 01/14] virt: sev-guest: Use AES GCM crypto library Nikunj A Dadhania
2023-10-30 17:51 ` Tom Lendacky
2023-11-02 3:33 ` Nikunj A. Dadhania
2023-10-30 6:36 ` [PATCH v5 02/14] virt: sev-guest: Move mutex to SNP guest device structure Nikunj A Dadhania
2023-10-30 6:36 ` [PATCH v5 03/14] virt: sev-guest: Replace dev_dbg with pr_debug Nikunj A Dadhania
2023-10-30 6:36 ` [PATCH v5 04/14] virt: sev-guest: Add SNP guest request structure Nikunj A Dadhania
2023-10-30 18:16 ` Tom Lendacky
2023-11-02 4:01 ` Nikunj A. Dadhania
2023-10-30 6:36 ` [PATCH v5 05/14] virt: sev-guest: Add vmpck_id to snp_guest_dev struct Nikunj A Dadhania
2023-10-30 16:16 ` Dionna Amalie Glaze
2023-10-30 17:12 ` Tom Lendacky
2023-11-02 4:03 ` Nikunj A. Dadhania
2023-10-30 18:26 ` Tom Lendacky
2023-10-30 6:36 ` [PATCH v5 06/14] x86/sev: Cache the secrets page address Nikunj A Dadhania
2023-10-30 6:36 ` [PATCH v5 07/14] x86/sev: Move and reorganize sev guest request api Nikunj A Dadhania
2023-10-30 19:16 ` Tom Lendacky
2023-11-02 4:28 ` Nikunj A. Dadhania
2023-11-02 14:17 ` Tom Lendacky
2023-10-30 6:36 ` [PATCH v5 08/14] x86/mm: Add generic guest initialization hook Nikunj A Dadhania
2023-10-30 17:23 ` Dave Hansen
2023-11-02 4:30 ` Nikunj A. Dadhania
2023-10-30 19:19 ` Tom Lendacky
2023-11-02 5:08 ` Nikunj A. Dadhania
2023-10-30 6:36 ` [PATCH v5 09/14] x86/sev: Add Secure TSC support for SNP guests Nikunj A Dadhania
2023-10-30 16:46 ` Dionna Amalie Glaze
2023-11-02 5:13 ` Nikunj A. Dadhania
2023-10-30 20:26 ` Tom Lendacky
2023-11-02 5:36 ` Nikunj A. Dadhania
2023-11-02 14:29 ` Tom Lendacky
2023-11-02 5:41 ` Nikunj A. Dadhania
2023-11-02 10:36 ` Kirill A. Shutemov
2023-11-06 10:45 ` Nikunj A. Dadhania
2023-11-06 13:00 ` Kirill A. Shutemov
2023-10-30 6:36 ` [PATCH v5 10/14] x86/sev: Change TSC MSR behavior for Secure TSC enabled guests Nikunj A Dadhania
2023-10-30 6:36 ` [PATCH v5 11/14] x86/sev: Prevent RDTSC/RDTSCP interception " Nikunj A Dadhania
2023-10-30 20:32 ` Tom Lendacky
2023-11-02 5:47 ` Nikunj A. Dadhania
2023-10-30 6:36 ` [PATCH v5 12/14] x86/kvmclock: Skip kvmclock when Secure TSC is available Nikunj A Dadhania
2023-10-30 21:00 ` Tom Lendacky
2023-11-02 5:39 ` Nikunj A. Dadhania
2023-10-30 6:36 ` [PATCH v5 13/14] x86/tsc: Mark Secure TSC as reliable clocksource Nikunj A Dadhania
2023-10-30 17:18 ` Dave Hansen
2023-11-02 5:53 ` Nikunj A. Dadhania
2023-11-02 10:33 ` Kirill A. Shutemov
2023-11-02 12:07 ` Nikunj A. Dadhania
2023-11-02 12:16 ` Nikunj A. Dadhania
2023-11-02 12:38 ` Kirill A. Shutemov [this message]
2023-11-06 11:53 ` Nikunj A. Dadhania
2023-11-06 13:03 ` Kirill A. Shutemov
2023-10-30 6:36 ` [PATCH v5 14/14] x86/sev: Enable Secure TSC for SNP guests Nikunj A Dadhania
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