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From: Ashish Kalra <ashish.kalra@amd.com>
To: Borislav Petkov <bp@alien8.de>
Cc: pbonzini@redhat.com, tglx@linutronix.de, mingo@redhat.com,
	hpa@zytor.com, joro@8bytes.org, bp@suse.de,
	thomas.lendacky@amd.com, x86@kernel.org, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org, srutherford@google.com,
	seanjc@google.com, venu.busireddy@oracle.com,
	brijesh.singh@amd.com, kexec@lists.infradead.org
Subject: Re: [PATCH v13 12/12] x86/kvm: Add guest support for detecting and enabling SEV Live Migration feature.
Date: Wed, 21 Apr 2021 15:22:20 +0000
Message-ID: <20210421152220.GB14004@ashkalra_ubuntu_server> (raw)
In-Reply-To: <20210421144402.GB5004@zn.tnic>

On Wed, Apr 21, 2021 at 04:44:02PM +0200, Borislav Petkov wrote:
> On Thu, Apr 15, 2021 at 04:01:16PM +0000, Ashish Kalra wrote:
> > From: Ashish Kalra <ashish.kalra@amd.com>
> > 
> > The guest support for detecting and enabling SEV Live migration
> > feature uses the following logic :
> > 
> >  - kvm_init_plaform() invokes check_kvm_sev_migration() which
> >    checks if its booted under the EFI
> > 
> >    - If not EFI,
> > 
> >      i) check for the KVM_FEATURE_CPUID
> 
> Where do you do that?
> 
> $ git grep KVM_FEATURE_CPUID
> $
> 
> Do you mean
> 
> 	kvm_para_has_feature(KVM_FEATURE_SEV_LIVE_MIGRATION)
> 
> per chance?
> 

Yes, the above mentions to get KVM_FEATURE_CPUID and then check if live
migration feature is supported, i.e.,
kvm_para_has_feature(KVM_FEATURE_SEV_LIVE_MIGRATION). The above comments
are written more generically.

> > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> > index 78bb0fae3982..94ef16d263a7 100644
> > --- a/arch/x86/kernel/kvm.c
> > +++ b/arch/x86/kernel/kvm.c
> > @@ -26,6 +26,7 @@
> >  #include <linux/kprobes.h>
> >  #include <linux/nmi.h>
> >  #include <linux/swait.h>
> > +#include <linux/efi.h>
> >  #include <asm/timer.h>
> >  #include <asm/cpu.h>
> >  #include <asm/traps.h>
> > @@ -429,6 +430,59 @@ static inline void __set_percpu_decrypted(void *ptr, unsigned long size)
> >  	early_set_memory_decrypted((unsigned long) ptr, size);
> >  }
> >  
> > +static int __init setup_kvm_sev_migration(void)
> 
> kvm_init_sev_migration() or so.
> 
> ...
> 
> > @@ -48,6 +50,8 @@ EXPORT_SYMBOL_GPL(sev_enable_key);
> >  
> >  bool sev_enabled __section(".data");
> >  
> > +bool sev_live_migration_enabled __section(".data");
> 
> Pls add a function called something like:
> 
> bool sev_feature_enabled(enum sev_feature)
> 
> and gets SEV_FEATURE_LIVE_MIGRATION and then use it instead of adding
> yet another boolean which contains whether some aspect of SEV has been
> enabled or not.
> 
> Then add a
> 
> static enum sev_feature sev_features;
> 
> in mem_encrypt.c and that function above will query that sev_features
> enum for set flags.
> 
> Then, if you feel bored, you could convert sme_active, sev_active,
> sev_es_active, mem_encrypt_active and whetever else code needs to query
> any aspect of SEV being enabled or not, to that function.
> 

Ok.

> > +void __init check_kvm_sev_migration(void)
> > +{
> > +	if (sev_active() &&
> > +	    kvm_para_has_feature(KVM_FEATURE_SEV_LIVE_MIGRATION)) {
> 
> Save an indentation level:
> 
> 	if (!sev_active() ||
> 	    !kvm_para_has_feature(KVM_FEATURE_SEV_LIVE_MIGRATION))
> 		return;
> 
> > +		unsigned long nr_pages;
> > +		int i;
> > +
> > +		pr_info("KVM enable live migration\n");
> 
> That should be at the end of the function and say:
> 
> 		pr_info("KVM live migration enabled.\n");
> 
> > +		WRITE_ONCE(sev_live_migration_enabled, true);
> 
> Why WRITE_ONCE?
> 

Just to ensure that the sev_live_migration_enabled is set to TRUE before
it is used immediately next in the function.

Thanks,
Ashish

> And that needs to go to the end of the function too.
> 
> Thx.
> 
> -- 
> Regards/Gruss,
>     Boris.
> 
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpeople.kernel.org%2Ftglx%2Fnotes-about-netiquette&amp;data=04%7C01%7CAshish.Kalra%40amd.com%7Cfe47697d718c4326b62108d904d3e9ad%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637546130496140162%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=d%2F%2Bx8t8R7zJclA7ENc%2Fxwt5%2FU13m%2FWObem2Hq8yH190%3D&amp;reserved=0

  reply index

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-15 15:52 [PATCH v13 00/12] Add AMD SEV guest live migration support Ashish Kalra
2021-04-15 15:53 ` [PATCH v13 01/12] KVM: SVM: Add KVM_SEV SEND_START command Ashish Kalra
2021-04-20  8:50   ` Paolo Bonzini
2021-04-15 15:53 ` [PATCH v13 02/12] KVM: SVM: Add KVM_SEND_UPDATE_DATA command Ashish Kalra
2021-04-15 15:54 ` [PATCH v13 03/12] KVM: SVM: Add KVM_SEV_SEND_FINISH command Ashish Kalra
2021-04-15 15:54 ` [PATCH v13 04/12] KVM: SVM: Add support for KVM_SEV_RECEIVE_START command Ashish Kalra
2021-04-20  8:38   ` Paolo Bonzini
2021-04-20  9:18     ` Paolo Bonzini
2021-04-15 15:55 ` [PATCH v13 05/12] KVM: SVM: Add KVM_SEV_RECEIVE_UPDATE_DATA command Ashish Kalra
2021-04-20  8:40   ` Paolo Bonzini
2021-04-20  8:43     ` Paolo Bonzini
2021-04-15 15:55 ` [PATCH v13 06/12] KVM: SVM: Add KVM_SEV_RECEIVE_FINISH command Ashish Kalra
2021-04-15 15:56 ` [PATCH v13 07/12] KVM: x86: Add AMD SEV specific Hypercall3 Ashish Kalra
2021-04-15 15:57 ` [PATCH v13 08/12] KVM: X86: Introduce KVM_HC_PAGE_ENC_STATUS hypercall Ashish Kalra
2021-04-20 11:10   ` Paolo Bonzini
2021-04-20 17:24     ` Sean Christopherson
2021-04-15 15:57 ` [PATCH v13 09/12] mm: x86: Invoke hypercall when page encryption status is changed Ashish Kalra
2021-04-20  9:39   ` Paolo Bonzini
2021-04-21 10:05   ` Borislav Petkov
2021-04-21 12:00     ` Paolo Bonzini
2021-04-21 14:09       ` Borislav Petkov
2021-04-21 12:12     ` Ashish Kalra
2021-04-21 13:50       ` Brijesh Singh
2021-04-21 13:52       ` Borislav Petkov
2021-04-15 15:58 ` [PATCH v13 10/12] KVM: x86: Introduce new KVM_FEATURE_SEV_LIVE_MIGRATION feature & Custom MSR Ashish Kalra
2021-04-19 23:06   ` Sean Christopherson
2021-04-20 10:49     ` Paolo Bonzini
2021-04-20  9:47   ` Paolo Bonzini
2021-04-15 15:58 ` [PATCH v13 11/12] EFI: Introduce the new AMD Memory Encryption GUID Ashish Kalra
2021-04-15 16:01 ` [PATCH v13 12/12] x86/kvm: Add guest support for detecting and enabling SEV Live Migration feature Ashish Kalra
2021-04-20 10:52   ` Paolo Bonzini
2021-04-21 14:44   ` Borislav Petkov
2021-04-21 15:22     ` Ashish Kalra [this message]
2021-04-21 15:32       ` Borislav Petkov
2021-04-21 15:38     ` Paolo Bonzini
2021-04-21 18:48       ` Ashish Kalra
2021-04-21 19:19         ` Ashish Kalra
2021-04-16 21:43 ` [PATCH v13 00/12] Add AMD SEV guest live migration support Steve Rutherford
2021-04-19 14:40   ` Ashish Kalra
2021-04-20 11:11 ` Paolo Bonzini
2021-04-20 18:51   ` Borislav Petkov
2021-04-20 19:08     ` Paolo Bonzini
2021-04-20 20:28       ` Borislav Petkov

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