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From: Borislav Petkov <bp@alien8.de>
To: Ashish Kalra <Ashish.Kalra@amd.com>
Cc: pbonzini@redhat.com, tglx@linutronix.de, mingo@redhat.com,
	hpa@zytor.com, joro@8bytes.org, 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
Subject: Re: [PATCH v13 09/12] mm: x86: Invoke hypercall when page encryption status is changed
Date: Wed, 21 Apr 2021 12:05:08 +0200
Message-ID: <20210421100508.GA11234@zn.tnic> (raw)
In-Reply-To: <f2340642c5b8d597a099285194fca8d05c9843bd.1618498113.git.ashish.kalra@amd.com>

On Thu, Apr 15, 2021 at 03:57:26PM +0000, Ashish Kalra wrote:
> +static inline void page_encryption_changed(unsigned long vaddr, int npages,
> +						bool enc)

When you see a function name "page_encryption_changed", what does that
tell you about what that function does?

Dunno but it doesn't tell me a whole lot.

Now look at the other function names in struct pv_mmu_ops.

See the difference?

> +static void set_memory_enc_dec_hypercall(unsigned long vaddr, int npages,

If I had to guess what that function does just by reading its name, it
sets a memory encryption/decryption hypercall.

Am I close?

> +					bool enc)
> +{
> +	unsigned long sz = npages << PAGE_SHIFT;
> +	unsigned long vaddr_end, vaddr_next;
> +
> +	vaddr_end = vaddr + sz;
> +
> +	for (; vaddr < vaddr_end; vaddr = vaddr_next) {
> +		int psize, pmask, level;
> +		unsigned long pfn;
> +		pte_t *kpte;
> +
> +		kpte = lookup_address(vaddr, &level);
> +		if (!kpte || pte_none(*kpte))
> +			return;
> +
> +		switch (level) {
> +		case PG_LEVEL_4K:
> +			pfn = pte_pfn(*kpte);
> +			break;
> +		case PG_LEVEL_2M:
> +			pfn = pmd_pfn(*(pmd_t *)kpte);
> +			break;
> +		case PG_LEVEL_1G:
> +			pfn = pud_pfn(*(pud_t *)kpte);
> +			break;
> +		default:
> +			return;
> +		}

Pretty much that same thing is in __set_clr_pte_enc(). Make a helper
function pls.

> +
> +		psize = page_level_size(level);
> +		pmask = page_level_mask(level);
> +
> +		kvm_sev_hypercall3(KVM_HC_PAGE_ENC_STATUS,
> +				   pfn << PAGE_SHIFT, psize >> PAGE_SHIFT, enc);
> +
> +		vaddr_next = (vaddr & pmask) + psize;
> +	}

As with other patches from Brijesh, that should be a while loop. :)

> +}
> +
>  static void __init __set_clr_pte_enc(pte_t *kpte, int level, bool enc)
>  {
>  	pgprot_t old_prot, new_prot;
> @@ -286,12 +329,13 @@ static void __init __set_clr_pte_enc(pte_t *kpte, int level, bool enc)
>  static int __init early_set_memory_enc_dec(unsigned long vaddr,
>  					   unsigned long size, bool enc)
>  {
> -	unsigned long vaddr_end, vaddr_next;
> +	unsigned long vaddr_end, vaddr_next, start;
>  	unsigned long psize, pmask;
>  	int split_page_size_mask;
>  	int level, ret;
>  	pte_t *kpte;
>  
> +	start = vaddr;
>  	vaddr_next = vaddr;
>  	vaddr_end = vaddr + size;
>  
> @@ -346,6 +390,8 @@ static int __init early_set_memory_enc_dec(unsigned long vaddr,
>  
>  	ret = 0;
>  
> +	set_memory_enc_dec_hypercall(start, PAGE_ALIGN(size) >> PAGE_SHIFT,
> +					enc);
>  out:
>  	__flush_tlb_all();
>  	return ret;
> @@ -481,6 +527,15 @@ void __init mem_encrypt_init(void)
>  	if (sev_active() && !sev_es_active())
>  		static_branch_enable(&sev_enable_key);
>  
> +#ifdef CONFIG_PARAVIRT
> +	/*
> +	 * With SEV, we need to make a hypercall when page encryption state is
> +	 * changed.
> +	 */
> +	if (sev_active())
> +		pv_ops.mmu.page_encryption_changed = set_memory_enc_dec_hypercall;
> +#endif

There's already a sev_active() check above it. Merge the two pls.

> +
>  	print_mem_encrypt_feature_info();
>  }
>  
> diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
> index 16f878c26667..3576b583ac65 100644
> --- a/arch/x86/mm/pat/set_memory.c
> +++ b/arch/x86/mm/pat/set_memory.c
> @@ -27,6 +27,7 @@
>  #include <asm/proto.h>
>  #include <asm/memtype.h>
>  #include <asm/set_memory.h>
> +#include <asm/paravirt.h>
>  
>  #include "../mm_internal.h"
>  
> @@ -2012,6 +2013,12 @@ static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
>  	 */
>  	cpa_flush(&cpa, 0);
>  
> +	/* Notify hypervisor that a given memory range is mapped encrypted
> +	 * or decrypted. The hypervisor will use this information during the
> +	 * VM migration.
> +	 */

Kernel comments style is:

	/*
	 * A sentence ending with a full-stop.
	 * Another sentence. ...
	 * More sentences. ...
	 */

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

  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 [this message]
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
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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