KVM Archive on lore.kernel.org
 help / color / Atom feed
From: Paolo Bonzini <pbonzini@redhat.com>
To: Borislav Petkov <bp@alien8.de>, Ashish Kalra <Ashish.Kalra@amd.com>
Cc: 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 17:38:45 +0200
Message-ID: <2d3170ae-470a-089d-bdec-a43f8190cce7@redhat.com> (raw)
In-Reply-To: <20210421144402.GB5004@zn.tnic>

On 21/04/21 16:44, 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?

Yep.  Or KVM_CPUID_FEATURES perhaps.

> 
>> 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.

Even better: let's stop callings things SEV/SEV_ES.  Long term we want 
anyway to use things like mem_encrypt_enabled (SEV), 
guest_instruction_trap_enabled (SEV/ES), etc.

For this one we don't need a bool at all, we can simply check whether 
the pvop points to paravirt_nop.  Also keep everything but the BSS 
handling in arch/x86/kernel/kvm.c.  Only the BSS handling should be in 
arch/x86/mm/mem_encrypt.c.  This way all KVM paravirt hypercalls and 
MSRs are in kvm.c.

That is:

void kvm_init_platform(void)
{
	if (sev_active() &&
	    kvm_para_has_feature(KVM_FEATURE_SEV_LIVE_MIGRATION)) {
		pv_ops.mmu.notify_page_enc_status_changed =
			kvm_sev_hc_page_enc_status;
		/* this takes care of bss_decrypted */
		early_set_page_enc_status();
		if (!efi_enabled(EFI_BOOT))
			wrmsrl(MSR_KVM_SEV_LIVE_MIGRATION,
			       KVM_SEV_LIVE_MIGRATION_ENABLED);
	}
	/* existing kvm_init_platform code goes here */
}

// the pvop is changed to take the pfn, so that the vaddr loop
// is not KVM specific
static inline void notify_page_enc_status_changed(unsigned long pfn,
				int npages, bool enc)
{
	PVOP_VCALL3(mmu.page_encryption_changed, pfn, npages, enc);
}

static void notify_addr_enc_status_changed(unsigned long addr,
					   int numpages, bool enc)
{
#ifdef CONFIG_PARAVIRT
	if (pv_ops.mmu.notify_page_enc_status_changed == paravirt_nop)
		return;

	/* the body of set_memory_enc_dec_hypercall goes here */
	for (; vaddr < vaddr_end; vaddr = vaddr_next) {
		...
		notify_page_enc_status_changed(pfn, psize >> PAGE_SHIFT,
					       enc);
		vaddr_next = (vaddr & pmask) + psize;
	}
#endif
}

static int __set_memory_enc_dec(unsigned long addr,
				int numpages, bool enc)
{
	...
  	cpa_flush(&cpa, 0);
	notify_addr_enc_status_changed(addr, numpages, enc);
  	return ret;
}


> +static int __init setup_kvm_sev_migration(void)

Please rename this to include efi in the function name.

> 
> +		 */
> +		if (!efi_enabled(EFI_BOOT))
> +			wrmsrl(MSR_KVM_SEV_LIVE_MIGRATION,
> +			       KVM_SEV_LIVE_MIGRATION_ENABLED);
> +		} else {
> +			pr_info("KVM enable live migration feature unsupported\n");
> +		}
> +}

I think this pr_info is incorrect, because it can still be enabled in 
the late_initcall.  Just remove it as in the sketch above.

Paolo


  parent 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
2021-04-21 15:32       ` Borislav Petkov
2021-04-21 15:38     ` Paolo Bonzini [this message]
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

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=2d3170ae-470a-089d-bdec-a43f8190cce7@redhat.com \
    --to=pbonzini@redhat.com \
    --cc=Ashish.Kalra@amd.com \
    --cc=bp@alien8.de \
    --cc=bp@suse.de \
    --cc=brijesh.singh@amd.com \
    --cc=hpa@zytor.com \
    --cc=joro@8bytes.org \
    --cc=kexec@lists.infradead.org \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=seanjc@google.com \
    --cc=srutherford@google.com \
    --cc=tglx@linutronix.de \
    --cc=thomas.lendacky@amd.com \
    --cc=venu.busireddy@oracle.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

KVM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/kvm/0 kvm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 kvm kvm/ https://lore.kernel.org/kvm \
		kvm@vger.kernel.org
	public-inbox-index kvm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.kvm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git