From: Borislav Petkov <bp@alien8.de>
To: Tom Lendacky <thomas.lendacky@amd.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
linux-coco@lists.linux.dev, svsm-devel@coconut-svsm.dev,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Dan Williams <dan.j.williams@intel.com>,
Michael Roth <michael.roth@amd.com>,
Ashish Kalra <ashish.kalra@amd.com>
Subject: Re: [PATCH v4 05/15] x86/sev: Use kernel provided SVSM Calling Areas
Date: Wed, 8 May 2024 10:05:09 +0200 [thread overview]
Message-ID: <20240508080509.GWZjsyNS0xBXUzKPUG@fat_crate.local> (raw)
In-Reply-To: <07266b47e749267ef9a9ccbc9e8e9df78ed54857.1713974291.git.thomas.lendacky@amd.com>
On Wed, Apr 24, 2024 at 10:58:01AM -0500, Tom Lendacky wrote:
> +static int __svsm_msr_protocol(struct svsm_call *call)
All those protocol functions need a verb in the name:
__svsm_do_msr_protocol
__svsm_do_ghcb_protocol
or something slicker than the silly "do".
> +{
> + u64 val, resp;
> + u8 pending;
> +
> + val = sev_es_rd_ghcb_msr();
> +
> + sev_es_wr_ghcb_msr(GHCB_MSR_VMPL_REQ_LEVEL(0));
> +
> + pending = 0;
Do that assignment above, at declaration.
> + issue_svsm_call(call, &pending);
> +
> + resp = sev_es_rd_ghcb_msr();
> +
> + sev_es_wr_ghcb_msr(val);
The MSR SVSM protocol is supposed to restore the MSR? A comment pls.
> +
> + if (pending)
> + return -EINVAL;
> +
> + if (GHCB_RESP_CODE(resp) != GHCB_MSR_VMPL_RESP)
> + return -EINVAL;
> +
> + if (GHCB_MSR_VMPL_RESP_VAL(resp) != 0)
s/ != 0//
> + return -EINVAL;
> +
> + return call->rax_out;
rax_out is u64, your function returns int because of the negative
values. But then it'll truncate the u64 in the success case.
> +}
> +
> +static int __svsm_ghcb_protocol(struct ghcb *ghcb, struct svsm_call *call)
> +{
> + struct es_em_ctxt ctxt;
> + u8 pending;
> +
> + vc_ghcb_invalidate(ghcb);
> +
> + /* Fill in protocol and format specifiers */
> + ghcb->protocol_version = ghcb_version;
> + ghcb->ghcb_usage = GHCB_DEFAULT_USAGE;
> +
> + ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_SNP_RUN_VMPL);
> + ghcb_set_sw_exit_info_1(ghcb, 0);
> + ghcb_set_sw_exit_info_2(ghcb, 0);
> +
> + sev_es_wr_ghcb_msr(__pa(ghcb));
> +
> + pending = 0;
As above.
> + issue_svsm_call(call, &pending);
> +
> + if (pending)
> + return -EINVAL;
> +
> + switch (verify_exception_info(ghcb, &ctxt)) {
> + case ES_OK:
> + break;
> + case ES_EXCEPTION:
> + vc_forward_exception(&ctxt);
> + fallthrough;
> + default:
> + return -EINVAL;
> + }
> +
> + return call->rax_out;
As above.
> +}
> +
> static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb,
> struct es_em_ctxt *ctxt,
> u64 exit_code, u64 exit_info_1,
> diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
> index a500df807e79..21f3cc40d662 100644
> --- a/arch/x86/kernel/sev.c
> +++ b/arch/x86/kernel/sev.c
> @@ -133,8 +133,13 @@ struct ghcb_state {
> struct ghcb *ghcb;
> };
>
> +/* For early boot SVSM communication */
> +static struct svsm_ca boot_svsm_ca_page __aligned(PAGE_SIZE);
> +
> static DEFINE_PER_CPU(struct sev_es_runtime_data*, runtime_data);
> static DEFINE_PER_CPU(struct sev_es_save_area *, sev_vmsa);
> +static DEFINE_PER_CPU(struct svsm_ca *, svsm_caa);
> +static DEFINE_PER_CPU(u64, svsm_caa_pa);
>
> struct sev_config {
> __u64 debug : 1,
> @@ -150,6 +155,15 @@ struct sev_config {
> */
> ghcbs_initialized : 1,
>
> + /*
> + * A flag used to indicate when the per-CPU SVSM CA is to be
s/A flag used //
and above.
> + * used instead of the boot SVSM CA.
> + *
> + * For APs, the per-CPU SVSM CA is created as part of the AP
> + * bringup, so this flag can be used globally for the BSP and APs.
> + */
> + cas_initialized : 1,
> +
> __reserved : 62;
> };
>
> @@ -572,9 +586,42 @@ static enum es_result vc_ioio_check(struct es_em_ctxt *ctxt, u16 port, size_t si
> return ES_EXCEPTION;
> }
>
> +static __always_inline void vc_forward_exception(struct es_em_ctxt *ctxt)
> +{
> + long error_code = ctxt->fi.error_code;
> + int trapnr = ctxt->fi.vector;
> +
> + ctxt->regs->orig_ax = ctxt->fi.error_code;
> +
> + switch (trapnr) {
> + case X86_TRAP_GP:
> + exc_general_protection(ctxt->regs, error_code);
> + break;
> + case X86_TRAP_UD:
> + exc_invalid_op(ctxt->regs);
> + break;
> + case X86_TRAP_PF:
> + write_cr2(ctxt->fi.cr2);
> + exc_page_fault(ctxt->regs, error_code);
> + break;
> + case X86_TRAP_AC:
> + exc_alignment_check(ctxt->regs, error_code);
> + break;
> + default:
> + pr_emerg("Unsupported exception in #VC instruction emulation - can't continue\n");
> + BUG();
> + }
> +}
> +
> /* Include code shared with pre-decompression boot stage */
> #include "sev-shared.c"
>
> +static struct svsm_ca *__svsm_get_caa(void)
Why the "__" prefix?
I gon't see a svsm_get_caa() variant...
> +{
> + return sev_cfg.cas_initialized ? this_cpu_read(svsm_caa)
> + : boot_svsm_caa;
> +}
> +
> static noinstr void __sev_put_ghcb(struct ghcb_state *state)
> {
> struct sev_es_runtime_data *data;
> @@ -600,6 +647,42 @@ static noinstr void __sev_put_ghcb(struct ghcb_state *state)
> }
> }
>
> +static int svsm_protocol(struct svsm_call *call)
svsm_issue_protocol_call() or whatnot...
Btw, can all this svsm guest gunk live simply in a separate file? Or is
it going to need a lot of sev.c stuff exported through an internal.h
header?
Either that or prefix all SVSM handling functions with "svsm_" so that
there's at least some visibility which is which.
> +{
> + struct ghcb_state state;
> + unsigned long flags;
> + struct ghcb *ghcb;
> + int ret;
> +
> + /*
> + * This can be called very early in the boot, use native functions in
> + * order to avoid paravirt issues.
> + */
> + flags = native_save_fl();
> + if (flags & X86_EFLAGS_IF)
> + native_irq_disable();
Uff, conditional locking.
What's wrong with using local_irq_save/local_irq_restore?
> +
> + if (sev_cfg.ghcbs_initialized)
> + ghcb = __sev_get_ghcb(&state);
> + else if (boot_ghcb)
> + ghcb = boot_ghcb;
> + else
> + ghcb = NULL;
> +
> + do {
> + ret = ghcb ? __svsm_ghcb_protocol(ghcb, call)
> + : __svsm_msr_protocol(call);
> + } while (ret == SVSM_ERR_BUSY);
> +
> + if (sev_cfg.ghcbs_initialized)
> + __sev_put_ghcb(&state);
> +
> + if (flags & X86_EFLAGS_IF)
> + native_irq_enable();
> +
> + return ret;
> +}
...
> @@ -2095,6 +2188,50 @@ static __head struct cc_blob_sev_info *find_cc_blob(struct boot_params *bp)
> return cc_info;
> }
>
> +static __head void setup_svsm(struct cc_blob_sev_info *cc_info)
svsm_setup
> +{
> + struct svsm_call call = {};
> + int ret;
> + u64 pa;
> +
> + /*
> + * Record the SVSM Calling Area address (CAA) if the guest is not
> + * running at VMPL0. The CA will be used to communicate with the
> + * SVSM to perform the SVSM services.
> + */
> + setup_svsm_ca(cc_info);
> +
> + /* Nothing to do if not running under an SVSM. */
> + if (!vmpl)
> + return;
You set up stuff above and now you bail out?
Judging by setup_svsm_ca() you don't really need that vmpl var but you
can check
if (!boot_svsm_caa)
return;
to determine whether a SVSM was detected.
> +
> + /*
> + * It is very early in the boot and the kernel is running identity
> + * mapped but without having adjusted the pagetables to where the
> + * kernel was loaded (physbase), so the get the CA address using
s/the //
> + * RIP-relative addressing.
> + */
> + pa = (u64)&RIP_REL_REF(boot_svsm_ca_page);
> +
> + /*
> + * Switch over to the boot SVSM CA while the current CA is still
> + * addressable. There is no GHCB at this point so use the MSR protocol.
> + *
> + * SVSM_CORE_REMAP_CA call:
> + * RAX = 0 (Protocol=0, CallID=0)
> + * RCX = New CA GPA
> + */
> + call.caa = __svsm_get_caa();
> + call.rax = SVSM_CORE_CALL(SVSM_CORE_REMAP_CA);
> + call.rcx = pa;
> + ret = svsm_protocol(&call);
> + if (ret != SVSM_SUCCESS)
> + panic("Can't remap the SVSM CA, ret=%#x (%d)\n", ret, ret);
> +
> + boot_svsm_caa = (struct svsm_ca *)pa;
> + boot_svsm_caa_pa = pa;
Huh, setup_svsm_ca() already assigned those...
> bool __head snp_init(struct boot_params *bp)
> {
> struct cc_blob_sev_info *cc_info;
> @@ -2108,12 +2245,7 @@ bool __head snp_init(struct boot_params *bp)
>
> setup_cpuid_table(cc_info);
>
> - /*
> - * Record the SVSM Calling Area address (CAA) if the guest is not
> - * running at VMPL0. The CA will be used to communicate with the
> - * SVSM to perform the SVSM services.
> - */
> - setup_svsm_ca(cc_info);
> + setup_svsm(cc_info);
>
> /*
> * The CC blob will be used later to access the secrets page. Cache
> @@ -2306,3 +2438,12 @@ void sev_show_status(void)
> }
> pr_cont("\n");
> }
> +
> +void __init snp_remap_svsm_ca(void)
> +{
> + if (!vmpl)
> + return;
> +
> + /* Update the CAA to a proper kernel address */
> + boot_svsm_caa = &boot_svsm_ca_page;
> +}
> diff --git a/arch/x86/mm/mem_encrypt_amd.c b/arch/x86/mm/mem_encrypt_amd.c
> index 422602f6039b..6155020e4d2d 100644
> --- a/arch/x86/mm/mem_encrypt_amd.c
> +++ b/arch/x86/mm/mem_encrypt_amd.c
> @@ -2,7 +2,7 @@
> /*
> * AMD Memory Encryption Support
> *
> - * Copyright (C) 2016 Advanced Micro Devices, Inc.
> + * Copyright (C) 2016-2024 Advanced Micro Devices, Inc.
Are we doing that now?
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2024-05-08 8:05 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-24 15:57 [PATCH v4 00/15] Provide SEV-SNP support for running under an SVSM Tom Lendacky
2024-04-24 15:57 ` [PATCH v4 01/15] x86/sev: Shorten snp_secrets_page_layout to snp_secrets_page Tom Lendacky
2024-04-25 13:30 ` Borislav Petkov
2024-04-24 15:57 ` [PATCH v4 02/15] x86/sev: Rename snp_init() in the boot/compressed/sev.c file Tom Lendacky
2024-04-24 15:57 ` [PATCH v4 03/15] x86/sev: Make the VMPL0 checking more straight forward Tom Lendacky
2024-04-24 15:58 ` [PATCH v4 04/15] x86/sev: Check for the presence of an SVSM in the SNP Secrets page Tom Lendacky
2024-05-02 9:35 ` Borislav Petkov
2024-05-02 15:29 ` Tom Lendacky
2024-05-17 15:58 ` Borislav Petkov
2024-05-20 13:57 ` Tom Lendacky
2024-04-24 15:58 ` [PATCH v4 05/15] x86/sev: Use kernel provided SVSM Calling Areas Tom Lendacky
2024-05-03 10:34 ` Borislav Petkov
2024-05-06 10:09 ` Borislav Petkov
2024-05-06 13:14 ` Tom Lendacky
2024-05-06 14:14 ` Borislav Petkov
2024-05-08 8:05 ` Borislav Petkov [this message]
2024-05-08 19:13 ` Tom Lendacky
2024-05-08 19:40 ` Tom Lendacky
2024-05-08 19:58 ` Borislav Petkov
2024-05-08 20:09 ` Tom Lendacky
2024-05-17 19:23 ` Borislav Petkov
2024-04-24 15:58 ` [PATCH v4 06/15] x86/sev: Perform PVALIDATE using the SVSM when not at VMPL0 Tom Lendacky
2024-04-24 15:58 ` [PATCH v4 07/15] x86/sev: Use the SVSM to create a vCPU when not in VMPL0 Tom Lendacky
2024-04-24 15:58 ` [PATCH v4 08/15] x86/sev: Provide SVSM discovery support Tom Lendacky
2024-04-24 15:58 ` [PATCH v4 09/15] x86/sev: Provide guest VMPL level to userspace Tom Lendacky
2024-04-24 15:58 ` [PATCH v4 10/15] virt: sev-guest: Choose the VMPCK key based on executing VMPL Tom Lendacky
2024-05-01 23:57 ` [svsm-devel] " Jacob Xu
2024-05-02 13:17 ` Tom Lendacky
2024-04-24 15:58 ` [PATCH v4 11/15] configfs-tsm: Allow the privlevel_floor attribute to be updated Tom Lendacky
2024-04-26 20:51 ` Dan Williams
2024-04-24 15:58 ` [PATCH v4 12/15] fs/configfs: Add a callback to determine attribute visibility Tom Lendacky
2024-04-26 21:48 ` Dan Williams
2024-04-29 13:26 ` Tom Lendacky
2024-04-24 15:58 ` [PATCH v4 13/15] x86/sev: Take advantage of configfs visibility support in TSM Tom Lendacky
2024-04-26 21:58 ` Dan Williams
2024-04-29 13:35 ` Tom Lendacky
2024-04-29 14:28 ` Tom Lendacky
2024-05-01 19:28 ` Dan Williams
2024-05-01 5:18 ` Kuppuswamy Sathyanarayanan
2024-05-01 20:15 ` Dan Williams
2024-05-02 3:40 ` Kuppuswamy Sathyanarayanan
2024-05-02 17:29 ` Dan Williams
2024-05-03 16:10 ` Kuppuswamy Sathyanarayanan
2024-04-24 15:58 ` [PATCH v4 14/15] x86/sev: Extend the config-fs attestation support for an SVSM Tom Lendacky
2024-04-24 15:58 ` [PATCH v4 15/15] x86/sev: Allow non-VMPL0 execution when an SVSM is present Tom Lendacky
2024-05-03 11:37 ` [svsm-devel] " Jörg Rödel
2024-05-03 16:04 ` Borislav Petkov
2024-05-06 7:43 ` Jörg Rödel
2024-05-03 11:38 ` [svsm-devel] [PATCH v4 00/15] Provide SEV-SNP support for running under an SVSM Jörg Rödel
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=20240508080509.GWZjsyNS0xBXUzKPUG@fat_crate.local \
--to=bp@alien8.de \
--cc=ashish.kalra@amd.com \
--cc=dan.j.williams@intel.com \
--cc=dave.hansen@linux.intel.com \
--cc=hpa@zytor.com \
--cc=linux-coco@lists.linux.dev \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=michael.roth@amd.com \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=svsm-devel@coconut-svsm.dev \
--cc=tglx@linutronix.de \
--cc=thomas.lendacky@amd.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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).