From: "Michael Kelley (LINUX)" <mikelley@microsoft.com>
To: Tianyu Lan <ltykernel@gmail.com>,
KY Srinivasan <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
"wei.liu@kernel.org" <wei.liu@kernel.org>,
Dexuan Cui <decui@microsoft.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"bp@alien8.de" <bp@alien8.de>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
"x86@kernel.org" <x86@kernel.org>,
"hpa@zytor.com" <hpa@zytor.com>,
"daniel.lezcano@linaro.org" <daniel.lezcano@linaro.org>,
"arnd@arndb.de" <arnd@arndb.de>
Cc: Tianyu Lan <Tianyu.Lan@microsoft.com>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"vkuznets@redhat.com" <vkuznets@redhat.com>
Subject: RE: [PATCH V3 5/9] x86/hyperv: Use vmmcall to implement Hyper-V hypercall in sev-snp enlightened guest
Date: Wed, 26 Jul 2023 14:29:12 +0000 [thread overview]
Message-ID: <BYAPR21MB16880B1657BA4C907D002730D700A@BYAPR21MB1688.namprd21.prod.outlook.com> (raw)
In-Reply-To: <89c9f27c-f539-ef75-dc67-bdb0a8480c4b@gmail.com>
From: Tianyu Lan <ltykernel@gmail.com> Sent: Wednesday, July 26, 2023 6:47 AM
>
> On 7/26/2023 11:44 AM, Michael Kelley (LINUX) wrote:
> >> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> >> index 2fa38e9f6207..025eda129d99 100644
> >> --- a/arch/x86/include/asm/mshyperv.h
> >> +++ b/arch/x86/include/asm/mshyperv.h
> >> @@ -64,12 +64,12 @@ static inline u64 hv_do_hypercall(u64 control, void *input,
> void *output)
> >> if (!hv_hypercall_pg)
> >> return U64_MAX;
> >>
> >> - __asm__ __volatile__("mov %4, %%r8\n"
> >> - CALL_NOSPEC
> >> + __asm__ __volatile__("mov %[output], %%r8\n"
> >> + ALTERNATIVE("vmmcall", CALL_NOSPEC, X86_FEATURE_SEV_ES)
> > Since this code is for SEV-SNP, what's the thinking behind using
> > X86_FEATURE_SEV_ES in the ALTERNATIVE statements? Don't you need
> > to use X86_FEATURE_SEV_SNP (which is being added in another patch set that
> > Boris Petkov pointed out).
>
> Hi Michael:
> Thanks for your review. The patch mentioned by Boris has not been
> merged and so still use X86_FEATURE_SEV_ES here. We may replace the
> feature flag with X86_FEATURE_SEV_SNP after it's upstreamed.
>
Just so I'm clear, is it true that in an SEV-SNP VM, the CPUID flags for
SEV-ES *and* SEV-SNP are set? That would seem to be necessary for
your approach to work.
I wonder if it would be better to take the patch from Brijesh Singh
that adds X86_FEATURE_SEV_SNP and add it to your patch set (with
Brijesh's agreement, of course). That patch is small and straightforward.
> >
> > Also, does this patch depend on Peter Zijlstra's patch to support nested
> > ALTERNATIVE statements? If so, that needs to be called out, probably in
> > the cover letter. Peter's patch doesn't yet appear in linux-next.
> >
>
> It may work without Peterz's patch. Please see
> https://lkml.org/lkml/2023/6/27/520
> Peterz's patch optimizes ALTERNATIVE_n implementation with nested
> expression.
OK, good.
Michael
next prev parent reply other threads:[~2023-07-26 14:29 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-18 3:22 [PATCH V3 0/9] x86/hyperv: Add AMD sev-snp enlightened guest support on hyperv Tianyu Lan
2023-07-18 3:22 ` [PATCH V3 1/9] x86/hyperv: Add sev-snp enlightened guest static key Tianyu Lan
2023-07-26 3:26 ` Michael Kelley (LINUX)
2023-07-18 3:22 ` [PATCH V3 2/9] x86/hyperv: Set Virtual Trust Level in VMBus init message Tianyu Lan
2023-07-26 3:28 ` Michael Kelley (LINUX)
2023-07-18 3:22 ` [PATCH V3 3/9] x86/hyperv: Mark Hyper-V vp assist page unencrypted in SEV-SNP enlightened guest Tianyu Lan
2023-07-18 3:22 ` [PATCH V3 4/9] drivers: hv: Mark percpu hvcall input arg " Tianyu Lan
2023-07-18 3:22 ` [PATCH V3 5/9] x86/hyperv: Use vmmcall to implement Hyper-V hypercall in sev-snp " Tianyu Lan
2023-07-26 3:44 ` Michael Kelley (LINUX)
2023-07-26 13:47 ` Tianyu Lan
2023-07-26 14:29 ` Michael Kelley (LINUX) [this message]
2023-07-28 10:45 ` Tianyu Lan
2023-07-18 3:23 ` [PATCH V3 6/9] clocksource: hyper-v: Mark hyperv tsc page unencrypted " Tianyu Lan
2023-07-18 3:23 ` [PATCH V3 7/9] x86/hyperv: Initialize cpu and memory for SEV-SNP " Tianyu Lan
2023-07-26 4:26 ` Jinank Jain
2023-07-26 14:15 ` Tianyu Lan
2023-07-18 3:23 ` [PATCH V3 8/9] x86/hyperv: Add smp support for SEV-SNP guest Tianyu Lan
2023-07-18 3:23 ` [PATCH V3 9/9] x86/hyperv: Add hyperv-specific handling for VMMCALL under SEV-ES Tianyu Lan
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