From: Borislav Petkov <bp@alien8.de>
To: Ashish Kalra <Ashish.Kalra@amd.com>, seanjc@google.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,
venu.busireddy@oracle.com, brijesh.singh@amd.com
Subject: Re: [PATCH v2 2/4] mm: x86: Invoke hypercall when page encryption status is changed
Date: Wed, 12 May 2021 15:15:37 +0200 [thread overview]
Message-ID: <YJvU+RAvetAPT2XY@zn.tnic> (raw)
In-Reply-To: <ff68a73e0cdaf89e56add5c8b6e110df881fede1.1619193043.git.ashish.kalra@amd.com>
On Fri, Apr 23, 2021 at 03:58:43PM +0000, Ashish Kalra wrote:
> +static inline void notify_page_enc_status_changed(unsigned long pfn,
> + int npages, bool enc)
> +{
> + PVOP_VCALL3(mmu.notify_page_enc_status_changed, pfn, npages, enc);
> +}
Now the question is whether something like that is needed for TDX, and,
if so, could it be shared by both.
Sean?
> +void notify_addr_enc_status_changed(unsigned long vaddr, int npages,
> + bool enc)
Let that line stick out.
> +{
> +#ifdef CONFIG_PARAVIRT
> + unsigned long sz = npages << PAGE_SHIFT;
> + unsigned long vaddr_end = vaddr + sz;
> +
> + while (vaddr < vaddr_end) {
> + int psize, pmask, level;
> + unsigned long pfn;
> + pte_t *kpte;
> +
> + kpte = lookup_address(vaddr, &level);
> + if (!kpte || pte_none(*kpte))
> + return;
What does this mean exactly? On the first failure to lookup the address,
you return? Why not continue so that you can notify about the remaining
pages in [vaddr - vaddr_end)?
Also, what does it mean for the current range if the lookup fails?
Innocuous situation or do you need to signal it with a WARN or so?
> +
> + pfn = pg_level_to_pfn(level, kpte, NULL);
> + if (!pfn)
> + continue;
Same here: if it hits the default case, wouldn't it make sense to
WARN_ONCE or so to catch potential misuse? Or better yet, the WARN_ONCE
should be in pg_level_to_pfn().
> diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
> index 16f878c26667..45e65517405a 100644
> --- a/arch/x86/mm/pat/set_memory.c
> +++ b/arch/x86/mm/pat/set_memory.c
> @@ -2012,6 +2012,13 @@ 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.
> + */
> + notify_addr_enc_status_changed(addr, numpages, enc);
If you notify about a range then that function should be called
notify_range_enc_status_changed
or so.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2021-05-12 13:15 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-23 15:57 [PATCH v2 0/4] Add guest support for SEV live migration Ashish Kalra
2021-04-23 15:58 ` [PATCH v2 1/4] KVM: x86: invert KVM_HYPERCALL to default to VMMCALL Ashish Kalra
2021-04-23 16:31 ` Jim Mattson
2021-04-23 17:44 ` Sean Christopherson
2021-04-23 15:58 ` [PATCH v2 2/4] mm: x86: Invoke hypercall when page encryption status is changed Ashish Kalra
2021-05-12 13:15 ` Borislav Petkov [this message]
2021-05-12 15:51 ` Sean Christopherson
2021-05-12 16:23 ` Borislav Petkov
2021-05-13 6:57 ` Ashish Kalra
2021-05-13 8:40 ` Paolo Bonzini
2021-05-13 13:49 ` Tom Lendacky
2021-05-13 4:34 ` Ashish Kalra
2021-05-14 7:33 ` Borislav Petkov
2021-05-14 8:03 ` Paolo Bonzini
2021-05-14 9:05 ` Ashish Kalra
2021-05-14 9:34 ` Borislav Petkov
2021-05-14 10:05 ` Ashish Kalra
2021-05-14 10:38 ` Borislav Petkov
2021-05-18 2:01 ` Steve Rutherford
2021-05-19 12:06 ` Ashish Kalra
2021-05-19 13:44 ` Paolo Bonzini
2021-05-14 9:57 ` Paolo Bonzini
2021-05-14 9:24 ` Borislav Petkov
2021-05-14 9:33 ` Ashish Kalra
2021-05-19 23:29 ` Andy Lutomirski
2021-05-19 23:44 ` Sean Christopherson
2021-04-23 15:59 ` [PATCH v2 3/4] EFI: Introduce the new AMD Memory Encryption GUID Ashish Kalra
2021-05-12 13:19 ` Borislav Petkov
2021-05-12 14:53 ` Ard Biesheuvel
2021-05-13 4:36 ` Ashish Kalra
2021-04-23 15:59 ` [PATCH v2 4/4] x86/kvm: Add guest support for detecting and enabling SEV Live Migration feature Ashish Kalra
2021-04-30 7:19 ` [PATCH v2 0/4] Add guest support for SEV live migration Ashish Kalra
2021-04-30 7:40 ` Paolo Bonzini
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