linux.git/arch/x86/kernel/sev-shared.c, branch v6.2

Revert "x86/sev: Expose sev_es_ghcb_hv_call() for use by HyperV"

2022-07-27T16:09:13+00:00

This reverts commit 007faec014cb5d26983c1f86fd08c6539b41392e.

Now that hyperv does its own protocol negotiation:

  49d6a3c062a1 ("x86/Hyper-V: Add SEV negotiate protocol support in Isolation VM")

revert this exposure of the sev_es_ghcb_hv_call() helper.

Cc: Wei Liu 
Signed-off-by: Borislav Petkov 
Reviewed-by：Tianyu Lan 
Link: https://lore.kernel.org/r/20220614014553.1915929-1-ltykernel@gmail.com

x86/sev: Remove duplicated assignment to variable info

2022-05-17T10:52:37+00:00

Variable info is being assigned the same value twice, remove the
redundant assignment. Also assign variable v in the declaration.

Cleans up clang scan warning:
  warning: Value stored to 'info' during its initialization is never read [deadcode.DeadStores]

No code changed:

  # arch/x86/kernel/sev.o:

   text    data     bss     dec     hex filename
  19878    4487    4112   28477    6f3d sev.o.before
  19878    4487    4112   28477    6f3d sev.o.after

md5:
   bfbaa515af818615fd01fea91e7eba1b  sev.o.before.asm
   bfbaa515af818615fd01fea91e7eba1b  sev.o.after.asm

  [ bp: Running the before/after check on sev.c because sev-shared.c
    gets included into it. ]

Fixes: 597cfe48212a ("x86/boot/compressed/64: Setup a GHCB-based VC Exception handler")
Signed-off-by: Colin Ian King 
Signed-off-by: Borislav Petkov 
Link: https://lore.kernel.org/r/20220516184215.51841-1-colin.i.king@gmail.com

x86/sev: Use firmware-validated CPUID for SEV-SNP guests

2022-04-07T14:47:12+00:00

SEV-SNP guests will be provided the location of special 'secrets' and
'CPUID' pages via the Confidential Computing blob. This blob is
provided to the run-time kernel either through a boot_params field that
was initialized by the boot/compressed kernel, or via a setup_data
structure as defined by the Linux Boot Protocol.

Locate the Confidential Computing blob from these sources and, if found,
use the provided CPUID page/table address to create a copy that the
run-time kernel will use when servicing CPUID instructions via a #VC
handler.

Signed-off-by: Michael Roth 
Signed-off-by: Brijesh Singh 
Signed-off-by: Borislav Petkov 
Link: https://lore.kernel.org/r/20220307213356.2797205-40-brijesh.singh@amd.com

x86/sev: Add SEV-SNP feature detection/setup

2022-04-07T14:47:11+00:00

Initial/preliminary detection of SEV-SNP is done via the Confidential
Computing blob. Check for it prior to the normal SEV/SME feature
initialization, and add some sanity checks to confirm it agrees with
SEV-SNP CPUID/MSR bits.

Signed-off-by: Michael Roth 
Signed-off-by: Brijesh Singh 
Signed-off-by: Borislav Petkov 
Link: https://lore.kernel.org/r/20220307213356.2797205-39-brijesh.singh@amd.com

x86/compressed/64: Add support for SEV-SNP CPUID table in #VC handlers

2022-04-07T14:47:11+00:00

CPUID instructions generate a #VC exception for SEV-ES/SEV-SNP guests,
for which early handlers are currently set up to handle. In the case
of SEV-SNP, guests can use a configurable location in guest memory
that has been pre-populated with a firmware-validated CPUID table to
look up the relevant CPUID values rather than requesting them from
hypervisor via a VMGEXIT. Add the various hooks in the #VC handlers to
allow CPUID instructions to be handled via the table. The code to
actually configure/enable the table will be added in a subsequent
commit.

Signed-off-by: Michael Roth 
Signed-off-by: Brijesh Singh 
Signed-off-by: Borislav Petkov 
Link: https://lore.kernel.org/r/20220307213356.2797205-33-brijesh.singh@amd.com

x86/sev: Move MSR-based VMGEXITs for CPUID to helper

2022-04-07T14:47:11+00:00

This code will also be used later for SEV-SNP-validated CPUID code in
some cases, so move it to a common helper.

While here, also add a check to terminate in cases where the CPUID
function/subfunction is indexed and the subfunction is non-zero, since
the GHCB MSR protocol does not support non-zero subfunctions.

Suggested-by: Sean Christopherson 
Signed-off-by: Michael Roth 
Signed-off-by: Brijesh Singh 
Signed-off-by: Borislav Petkov 
Link: https://lore.kernel.org/r/20220307213356.2797205-32-brijesh.singh@amd.com

x86/sev: Register GHCB memory when SEV-SNP is active

2022-04-06T11:16:58+00:00

The SEV-SNP guest is required by the GHCB spec to register the GHCB's
Guest Physical Address (GPA). This is because the hypervisor may prefer
that a guest uses a consistent and/or specific GPA for the GHCB associated
with a vCPU. For more information, see the GHCB specification section
"GHCB GPA Registration".

  [ bp: Cleanup comments. ]

Signed-off-by: Brijesh Singh 
Signed-off-by: Borislav Petkov 
Link: https://lore.kernel.org/r/20220307213356.2797205-18-brijesh.singh@amd.com

x86/compressed: Register GHCB memory when SEV-SNP is active

2022-04-06T11:14:24+00:00

The SEV-SNP guest is required by the GHCB spec to register the GHCB's
Guest Physical Address (GPA). 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".

If hypervisor can not work with the guest provided GPA then terminate the
guest boot.

Signed-off-by: Brijesh Singh 
Signed-off-by: Borislav Petkov 
Reviewed-by: Venu Busireddy 
Link: https://lore.kernel.org/r/20220307213356.2797205-17-brijesh.singh@amd.com

x86/sev: Check SEV-SNP features support

2022-04-06T11:10:23+00:00

Version 2 of the GHCB specification added the advertisement of features
that are supported by the hypervisor. If the hypervisor supports SEV-SNP
then it must set the SEV-SNP features bit to indicate that the base
functionality is supported.

Check that feature bit while establishing the GHCB; if failed, terminate
the guest.

Version 2 of the GHCB specification adds several new Non-Automatic Exits
(NAEs), most of them are optional except the hypervisor feature. Now
that the hypervisor feature NAE is implemented, bump the GHCB maximum
supported protocol version.

While at it, move the GHCB protocol negotiation check from the #VC
exception handler to sev_enable() so that all feature detection happens
before the first #VC exception.

While at it, document why the GHCB page cannot be setup from
load_stage2_idt().

  [ bp: Massage commit message. ]

Signed-off-by: Brijesh Singh 
Signed-off-by: Borislav Petkov 
Link: https://lore.kernel.org/r/20220307213356.2797205-13-brijesh.singh@amd.com

x86/sev: Save the negotiated GHCB version

2022-04-06T11:10:18+00:00

The SEV-ES guest calls sev_es_negotiate_protocol() to negotiate the GHCB
protocol version before establishing the GHCB. Cache the negotiated GHCB
version so that it can be used later.

Signed-off-by: Brijesh Singh 
Signed-off-by: Borislav Petkov 
Reviewed-by: Venu Busireddy 
Link: https://lore.kernel.org/r/20220307213356.2797205-12-brijesh.singh@amd.com