From: Wei Hu <weh@linux.microsoft.com>
To: linux-hyperv@vger.kernel.org
Cc: linux-kernel@vger.kernel.org,
"K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
Long Li <longli@microsoft.com>
Subject: [PATCH v1 07/13] mshv: default to safe partition CPU features
Date: Fri, 7 Aug 2026 13:51:13 +0000 [thread overview]
Message-ID: <20260807135134.303943-8-weh@linux.microsoft.com> (raw)
In-Reply-To: <20260807135134.303943-1-weh@linux.microsoft.com>
From: Wei Liu <wei.liu@kernel.org>
For legacy create-partition callers, disable all processor and xsave
features first, then enable only the default feature set known to be
supported. Passing an all-zero disabled feature mask can make SEV-SNP
partition creation fail on Hyper-V.
Signed-off-by: Wei Liu <wei.liu@kernel.org>
---
drivers/hv/mshv_root_main.c | 90 ++++++++++++++++++++++++++++++++-----
1 file changed, 80 insertions(+), 10 deletions(-)
diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
index cc38507570ac..11d3c86050b4 100644
--- a/drivers/hv/mshv_root_main.c
+++ b/drivers/hv/mshv_root_main.c
@@ -2333,6 +2333,86 @@ static long mshv_ioctl_process_pt_flags(void __user *user_arg, u64 *pt_flags,
disabled_procs = &cr_props->disabled_processor_features;
disabled_xsave = &cr_props->disabled_processor_xsave_features;
+ /* Disable all processor features first. */
+ for (i = 0; i < HV_PARTITION_PROCESSOR_FEATURES_BANKS; i++)
+ disabled_procs->as_uint64[i] = U64_MAX;
+
+#if IS_ENABLED(CONFIG_X86_64)
+ /* Enable default features that are known to be supported. */
+ disabled_procs->sse3_support = 0;
+ disabled_procs->lahf_sahf_support = 0;
+ disabled_procs->ssse3_support = 0;
+ disabled_procs->sse4_1_support = 0;
+ disabled_procs->sse4_2_support = 0;
+ disabled_procs->sse4a_support = 0;
+ disabled_procs->xop_support = 0;
+ disabled_procs->pop_cnt_support = 0;
+ disabled_procs->cmpxchg16b_support = 0;
+ disabled_procs->altmovcr8_support = 0;
+ disabled_procs->lzcnt_support = 0;
+ disabled_procs->mis_align_sse_support = 0;
+ disabled_procs->mmx_ext_support = 0;
+ disabled_procs->amd3dnow_support = 0;
+ disabled_procs->extended_amd3dnow_support = 0;
+ disabled_procs->page_1gb_support = 0;
+ disabled_procs->aes_support = 0;
+ disabled_procs->pclmulqdq_support = 0;
+ disabled_procs->pcid_support = 0;
+ disabled_procs->fma4_support = 0;
+ disabled_procs->f16c_support = 0;
+ disabled_procs->rd_rand_support = 0;
+ disabled_procs->rd_wr_fs_gs_support = 0;
+ disabled_procs->smep_support = 0;
+ disabled_procs->enhanced_fast_string_support = 0;
+ disabled_procs->bmi1_support = 0;
+ disabled_procs->bmi2_support = 0;
+ disabled_procs->hle_support_deprecated = 0;
+ disabled_procs->rtm_support_deprecated = 0;
+ disabled_procs->movbe_support = 0;
+ disabled_procs->npiep1_support = 0;
+ disabled_procs->dep_x87_fpu_save_support = 0;
+ disabled_procs->rd_seed_support = 0;
+ disabled_procs->adx_support = 0;
+ disabled_procs->intel_prefetch_support = 0;
+ disabled_procs->smap_support = 0;
+ disabled_procs->hle_support = 0;
+ disabled_procs->rtm_support = 0;
+ disabled_procs->rdtscp_support = 0;
+ disabled_procs->clflushopt_support = 0;
+ disabled_procs->invpcid_support = 0;
+ disabled_procs->ibrs_support = 0;
+ disabled_procs->stibp_support = 0;
+ disabled_procs->ibpb_support = 0;
+ disabled_procs->unrestricted_guest_support = 0;
+ disabled_procs->mdd_support = 0;
+ disabled_procs->fast_short_rep_mov_support = 0;
+ disabled_procs->l1dcache_flush_support = 0;
+ disabled_procs->rdcl_no_support = 0;
+ disabled_procs->ibrs_all_support = 0;
+ disabled_procs->skip_l1df_support = 0;
+ disabled_procs->ssb_no_support = 0;
+ disabled_procs->rsb_a_no_support = 0;
+ disabled_procs->virt_spec_ctrl_support = 0;
+ disabled_procs->rd_pid_support = 0;
+ disabled_procs->umip_support = 0;
+ disabled_procs->mbs_no_support = 0;
+ disabled_procs->mb_clear_support = 0;
+ disabled_procs->taa_no_support = 0;
+ disabled_procs->tsx_ctrl_support = 0;
+ disabled_procs->tsc_invariant_support = 0;
+ disabled_procs->rdpru_support = 0;
+ disabled_procs->mbec_support = 0;
+ disabled_procs->psfd_support = 0;
+ disabled_procs->cet_ss_support = 0;
+ disabled_procs->cet_ibt_support = 0;
+ disabled_procs->vmx_exception_inject_support = 0;
+
+ disabled_xsave->as_uint64 = U64_MAX;
+ disabled_xsave->xsave_support = 0;
+ disabled_xsave->xsaveopt_support = 0;
+ disabled_xsave->avx_support = 0;
+#endif
+
/* Check if user provided newer struct with feature fields */
if (args.pt_flags & BIT_ULL(MSHV_PT_BIT_CPU_AND_XSAVE_FEATURES)) {
if (copy_from_user(&args, user_arg, sizeof(args)))
@@ -2371,16 +2451,6 @@ static long mshv_ioctl_process_pt_flags(void __user *user_arg, u64 *pt_flags,
if (mshv_field_nonzero(args, pt_rsvd2))
return -EINVAL;
#endif
- } else {
- /*
- * v1 behavior: try to enable everything. The hypervisor will
- * disable features that are not supported. The banks can be
- * queried via the get partition property hypercall.
- */
- for (i = 0; i < HV_PARTITION_PROCESSOR_FEATURES_BANKS; i++)
- disabled_procs->as_uint64[i] = 0;
-
- disabled_xsave->as_uint64 = 0;
}
/* Only support EXO partitions */
--
2.43.0
next prev parent reply other threads:[~2026-08-07 13:52 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-07 13:51 [PATCH v1 00/13] mshv: add SEV-SNP support for MSHV root partitions Wei Hu
2026-08-07 13:51 ` [PATCH v1 01/13] mshv: add SEV-SNP UAPI definitions Wei Hu
2026-08-07 13:51 ` [PATCH v1 02/13] mshv: add SEV-SNP PSP request hypercall Wei Hu
2026-08-07 13:51 ` [PATCH v1 03/13] mshv: add SEV-SNP isolated page hypercalls Wei Hu
2026-08-07 13:51 ` [PATCH v1 04/13] mshv: wire SEV-SNP partition ioctls Wei Hu
2026-08-07 13:51 ` [PATCH v1 05/13] hyperv: fix hv_input_get_system_property layout for SNP status Wei Hu
2026-08-07 13:51 ` [PATCH v1 06/13] mshv: detect and report SEV-SNP support at init Wei Hu
2026-08-07 13:51 ` Wei Hu [this message]
2026-08-07 13:51 ` [PATCH v1 08/13] mshv: accept partial CPU feature banks Wei Hu
2026-08-07 13:51 ` [PATCH v1 09/13] mshv: define full processor and xsave feature masks Wei Hu
2026-08-07 13:51 ` [PATCH v1 10/13] mshv: unmap SNP memory before state teardown Wei Hu
2026-08-07 13:51 ` [PATCH v1 11/13] mshv: unlock SNP pages on panic for crashdump collection Wei Hu
2026-08-07 13:51 ` [PATCH v1 12/13] hyperv: add MSHV Dom0 root-partition boot enablement (EFI HvLoader) Wei Hu
2026-08-07 13:51 ` [PATCH v1 13/13] mshv: set up own SynIC registers on a nested root partition Wei Hu
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=20260807135134.303943-8-weh@linux.microsoft.com \
--to=weh@linux.microsoft.com \
--cc=decui@microsoft.com \
--cc=haiyangz@microsoft.com \
--cc=kys@microsoft.com \
--cc=linux-hyperv@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=longli@microsoft.com \
--cc=wei.liu@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