From: Brijesh Singh <brijesh.singh@amd.com>
To: Borislav Petkov <bp@alien8.de>
Cc: brijesh.singh@amd.com, x86@kernel.org,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
tglx@linutronix.de, jroedel@suse.de, thomas.lendacky@amd.com,
pbonzini@redhat.com, mingo@redhat.com, dave.hansen@intel.com,
rientjes@google.com, seanjc@google.com, peterz@infradead.org,
hpa@zytor.com, tony.luck@intel.com
Subject: Re: [PATCH Part1 RFC v2 13/20] x86/sev: Register GHCB memory when SEV-SNP is active
Date: Tue, 25 May 2021 09:28:14 -0500 [thread overview]
Message-ID: <b15cd25b-ee69-237d-9044-84fba2cf4bb2@amd.com> (raw)
In-Reply-To: <YKzbfwD6nHL7ChcJ@zn.tnic>
On 5/25/21 6:11 AM, Borislav Petkov wrote:
> On Fri, Apr 30, 2021 at 07:16:09AM -0500, Brijesh Singh wrote:
>> The SEV-SNP guest is required to perform GHCB GPA registration. This is
>> because the hypervisor may prefer that a guest use a consistent and/or
>> specific GPA for the GHCB associated with a vCPU. For more information,
>> see the GHCB specification section GHCB GPA Registration.
>>
>> During the boot, init_ghcb() allocates a per-cpu GHCB page. On very first
>> VC exception, the exception handler switch to using the per-cpu GHCB page
>> allocated during the init_ghcb(). The GHCB page must be registered in
>> the current vcpu context.
>>
>> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
>> ---
>> arch/x86/kernel/sev.c | 21 +++++++++++++++++++++
>> 1 file changed, 21 insertions(+)
>>
>> diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
>> index 8c8c939a1754..e6819f170ec4 100644
>> --- a/arch/x86/kernel/sev.c
>> +++ b/arch/x86/kernel/sev.c
>> @@ -88,6 +88,13 @@ struct sev_es_runtime_data {
>> * is currently unsupported in SEV-ES guests.
>> */
>> unsigned long dr7;
>> +
>> + /*
>> + * SEV-SNP requires that the GHCB must be registered before using it.
>> + * The flag below will indicate whether the GHCB is registered, if its
>> + * not registered then sev_es_get_ghcb() will perform the registration.
>> + */
>> + bool snp_ghcb_registered;
>> };
>>
>> struct ghcb_state {
>> @@ -100,6 +107,9 @@ DEFINE_STATIC_KEY_FALSE(sev_es_enable_key);
>> /* Needed in vc_early_forward_exception */
>> void do_early_exception(struct pt_regs *regs, int trapnr);
>>
>> +/* Defined in sev-shared.c */
>> +static void snp_register_ghcb(unsigned long paddr);
> Can we get rid of those forward declarations pls? Due to sev-shared.c
> this file is starting to spawn those and that's ugly.
>
> Either through a code reorg or even defining a sev-internal.h header
> which contains all those so that they don't pollute the code?
Okay, I will see what I can do to avoid the forward declarations.
> Thx.
>
>> +
>> static void __init setup_vc_stacks(int cpu)
>> {
>> struct sev_es_runtime_data *data;
>> @@ -218,6 +228,12 @@ static __always_inline struct ghcb *sev_es_get_ghcb(struct ghcb_state *state)
>> data->ghcb_active = true;
>> }
>>
>> + /* SEV-SNP guest requires that GHCB must be registered before using it. */
>> + if (sev_snp_active() && !data->snp_ghcb_registered) {
>> + snp_register_ghcb(__pa(ghcb));
>> + data->snp_ghcb_registered = true;
>> + }
> More missed review from last time:
>
> "This needs to be set to true in the function itself, in the success
> case."
>
> Can you please be more careful and go through all review comments so
> that I don't have to do the same work twice?
I am not ignoring your valuable feedback; I am sorry if I came across
like that.
In this particular case, the snp_register_ghcb() is shared between the
decompress and main kernel. The variable data->snp_ghcb_registered is
not visible in the decompressed path, so I choose not to set it to true
inside the function itself.
> Thx.
>
next prev parent reply other threads:[~2021-05-25 14:28 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-30 12:15 [PATCH Part1 RFC v2 00/20] Add AMD Secure Nested Paging (SEV-SNP) Guest Support Brijesh Singh
2021-04-30 12:15 ` [PATCH Part1 RFC v2 01/20] x86/sev: Define the GHCB MSR protocol for AP reset hold Brijesh Singh
2021-04-30 12:15 ` [PATCH Part1 RFC v2 02/20] x86/sev: Save the negotiated GHCB version Brijesh Singh
2021-05-11 9:23 ` Borislav Petkov
2021-05-11 18:29 ` Brijesh Singh
2021-05-11 18:41 ` Borislav Petkov
2021-05-12 14:03 ` Brijesh Singh
2021-05-12 14:31 ` Borislav Petkov
2021-05-12 15:03 ` Brijesh Singh
2021-04-30 12:15 ` [PATCH Part1 RFC v2 03/20] x86/sev: Add support for hypervisor feature VMGEXIT Brijesh Singh
2021-05-11 10:01 ` Borislav Petkov
2021-05-11 18:53 ` Brijesh Singh
2021-05-17 14:40 ` Borislav Petkov
2021-04-30 12:16 ` [PATCH Part1 RFC v2 04/20] x86/sev: Increase the GHCB protocol version Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 05/20] x86/sev: Define SNP Page State Change VMGEXIT structure Brijesh Singh
2021-05-18 10:41 ` Borislav Petkov
2021-05-18 15:06 ` Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 06/20] x86/sev: Define SNP guest request NAE events Brijesh Singh
2021-05-18 10:45 ` Borislav Petkov
2021-05-18 13:42 ` Brijesh Singh
2021-05-18 13:54 ` Borislav Petkov
2021-05-18 14:13 ` Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 07/20] x86/sev: Define error codes for reason set 1 Brijesh Singh
2021-05-18 11:05 ` Borislav Petkov
2021-04-30 12:16 ` [PATCH Part1 RFC v2 08/20] x86/mm: Add sev_snp_active() helper Brijesh Singh
2021-05-18 18:11 ` Borislav Petkov
2021-05-19 17:28 ` Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 09/20] x86/sev: check SEV-SNP features support Brijesh Singh
2021-05-20 16:02 ` Borislav Petkov
2021-05-20 17:40 ` Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 10/20] x86/sev: Add a helper for the PVALIDATE instruction Brijesh Singh
2021-04-30 13:05 ` Brijesh Singh
2021-05-20 17:32 ` Borislav Petkov
2021-05-20 17:44 ` Brijesh Singh
2021-05-20 17:51 ` Borislav Petkov
2021-05-20 17:57 ` Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 11/20] x86/compressed: Add helper for validating pages in the decompression stage Brijesh Singh
2021-05-20 17:52 ` Borislav Petkov
2021-05-20 18:05 ` Brijesh Singh
2021-05-25 10:18 ` Borislav Petkov
2021-04-30 12:16 ` [PATCH Part1 RFC v2 12/20] x86/compressed: Register GHCB memory when SEV-SNP is active Brijesh Singh
2021-05-25 10:41 ` Borislav Petkov
2021-04-30 12:16 ` [PATCH Part1 RFC v2 13/20] x86/sev: " Brijesh Singh
2021-05-25 11:11 ` Borislav Petkov
2021-05-25 14:28 ` Brijesh Singh [this message]
2021-05-25 14:35 ` Borislav Petkov
2021-05-25 14:47 ` Brijesh Singh
2021-05-26 9:57 ` Borislav Petkov
2021-05-26 13:23 ` Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 14/20] x86/sev: Add helper for validating pages in early enc attribute changes Brijesh Singh
2021-05-26 10:39 ` Borislav Petkov
2021-05-26 13:34 ` Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 15/20] x86/kernel: Make the bss.decrypted section shared in RMP table Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 16/20] x86/kernel: Validate rom memory before accessing when SEV-SNP is active Brijesh Singh
2021-05-27 11:49 ` Borislav Petkov
2021-05-27 12:12 ` Brijesh Singh
2021-05-27 12:23 ` Borislav Petkov
2021-05-27 12:56 ` Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 17/20] x86/mm: Add support to validate memory when changing C-bit Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 18/20] x86/boot: Add Confidential Computing address to setup_header Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 19/20] x86/sev: Register SNP guest request platform device Brijesh Singh
2021-04-30 12:16 ` [PATCH Part1 RFC v2 20/20] virt: Add SEV-SNP guest driver Brijesh Singh
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