From: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
To: Borislav Petkov <bp@alien8.de>
Cc: linux-hyperv@vger.kernel.org, stefan.bader@canonical.com,
tim.gardner@canonical.com, roxana.nicolescu@canonical.com,
cascardo@canonical.com, kys@microsoft.com,
haiyangz@microsoft.com, wei.liu@kernel.org, sashal@kernel.org,
stable@vger.kernel.org, linux-kernel@vger.kernel.org,
"H. Peter Anvin" <hpa@zytor.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Michael Kelley <mhkelley58@gmail.com>,
Nikolay Borisov <nik.borisov@suse.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Tom Lendacky <thomas.lendacky@amd.com>,
x86@kernel.org, Dexuan Cui <decui@microsoft.com>
Subject: Re: [PATCH v1 1/3] x86/tdx: Check for TDX partitioning during early TDX init
Date: Wed, 22 Nov 2023 18:19:20 +0100 [thread overview]
Message-ID: <0799b692-4b26-4e00-9cec-fdc4c929ea58@linux.microsoft.com> (raw)
In-Reply-To: <20231122170106.270266-1-jpiotrowski@linux.microsoft.com>
On 22/11/2023 18:01, Jeremi Piotrowski wrote:
> Check for additional CPUID bits to identify TDX guests running with Trust
> Domain (TD) partitioning enabled. TD partitioning is like nested virtualization
> inside the Trust Domain so there is a L1 TD VM(M) and there can be L2 TD VM(s).
>
> In this arrangement we are not guaranteed that the TDX_CPUID_LEAF_ID is visible
> to Linux running as an L2 TD VM. This is because a majority of TDX facilities
> are controlled by the L1 VMM and the L2 TDX guest needs to use TD partitioning
> aware mechanisms for what's left. So currently such guests do not have
> X86_FEATURE_TDX_GUEST set.
>
> We want the kernel to have X86_FEATURE_TDX_GUEST set for all TDX guests so we
> need to check these additional CPUID bits, but we skip further initialization
> in the function as we aren't guaranteed access to TDX module calls.
>
> Cc: <stable@vger.kernel.org> # v6.5+
> Signed-off-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
> ---
> arch/x86/coco/tdx/tdx.c | 29 ++++++++++++++++++++++++++---
> arch/x86/include/asm/tdx.h | 3 +++
> 2 files changed, 29 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
> index 1d6b863c42b0..c7bbbaaf654d 100644
> --- a/arch/x86/coco/tdx/tdx.c
> +++ b/arch/x86/coco/tdx/tdx.c
> @@ -8,6 +8,7 @@
> #include <linux/export.h>
> #include <linux/io.h>
> #include <asm/coco.h>
> +#include <asm/hyperv-tlfs.h>
> #include <asm/tdx.h>
> #include <asm/vmx.h>
> #include <asm/insn.h>
> @@ -37,6 +38,8 @@
>
> #define TDREPORT_SUBTYPE_0 0
>
> +bool tdx_partitioning_active;
> +
> /* Called from __tdx_hypercall() for unrecoverable failure */
> noinstr void __tdx_hypercall_failed(void)
> {
> @@ -757,19 +760,38 @@ static bool tdx_enc_status_change_finish(unsigned long vaddr, int numpages,
> return true;
> }
>
> +
> +static bool early_is_hv_tdx_partitioning(void)
> +{
> + u32 eax, ebx, ecx, edx;
> + cpuid(HYPERV_CPUID_ISOLATION_CONFIG, &eax, &ebx, &ecx, &edx);
> + return eax & HV_PARAVISOR_PRESENT &&
> + (ebx & HV_ISOLATION_TYPE) == HV_ISOLATION_TYPE_TDX;
> +}
> +
> void __init tdx_early_init(void)
> {
> u64 cc_mask;
> u32 eax, sig[3];
>
> cpuid_count(TDX_CPUID_LEAF_ID, 0, &eax, &sig[0], &sig[2], &sig[1]);
> -
> - if (memcmp(TDX_IDENT, sig, sizeof(sig)))
> - return;
> + if (memcmp(TDX_IDENT, sig, sizeof(sig))) {
> + tdx_partitioning_active = early_is_hv_tdx_partitioning();
> + if (!tdx_partitioning_active)
> + return;
> + }
Hi Borislav,
Just wanted to run another option by you. Instead of checking the CPUID here we
could accomplish the same result by doing _this_ in the hyperv cc init:
diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index 8c6bf07f7d2b..705794642d34 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -595,6 +595,8 @@ void __init hv_vtom_init(void)
#endif
case HV_ISOLATION_TYPE_TDX:
+ setup_force_cpu_cap(X86_FEATURE_TDX_GUEST);
+ tdx_partitioning_active = true;
cc_vendor = CC_VENDOR_INTEL;
break;
Which approach do you prefer?
Thanks,
Jeremi
>
> setup_force_cpu_cap(X86_FEATURE_TDX_GUEST);
>
> cc_vendor = CC_VENDOR_INTEL;
> +
> + /*
> + * Need to defer cc_mask and page visibility callback initializations
> + * to a TD-partitioning aware implementation.
> + */
> + if (tdx_partitioning_active)
> + goto exit;
> +
> tdx_parse_tdinfo(&cc_mask);
> cc_set_mask(cc_mask);
>
> @@ -820,5 +842,6 @@ void __init tdx_early_init(void)
> */
> x86_cpuinit.parallel_bringup = false;
>
> +exit:
> pr_info("Guest detected\n");
> }
> diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
> index 603e6d1e9d4a..fe22f8675859 100644
> --- a/arch/x86/include/asm/tdx.h
> +++ b/arch/x86/include/asm/tdx.h
> @@ -52,6 +52,7 @@ bool tdx_early_handle_ve(struct pt_regs *regs);
>
> int tdx_mcall_get_report0(u8 *reportdata, u8 *tdreport);
>
> +extern bool tdx_partitioning_active;
> #else
>
> static inline void tdx_early_init(void) { };
> @@ -71,6 +72,8 @@ static inline long tdx_kvm_hypercall(unsigned int nr, unsigned long p1,
> {
> return -ENODEV;
> }
> +
> +#define tdx_partitioning_active false
> #endif /* CONFIG_INTEL_TDX_GUEST && CONFIG_KVM_GUEST */
> #endif /* !__ASSEMBLY__ */
> #endif /* _ASM_X86_TDX_H */
next prev parent reply other threads:[~2023-11-22 17:19 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-22 17:01 [PATCH v1 1/3] x86/tdx: Check for TDX partitioning during early TDX init Jeremi Piotrowski
2023-11-22 17:01 ` [PATCH v1 2/3] x86/coco: Disable TDX module calls when TD partitioning is active Jeremi Piotrowski
2023-11-23 14:13 ` Kirill A. Shutemov
2023-11-24 10:38 ` Jeremi Piotrowski
2023-11-29 10:37 ` Huang, Kai
2023-12-01 15:27 ` Jeremi Piotrowski
2023-11-22 17:01 ` [PATCH v1 3/3] x86/tdx: Provide stub tdx_accept_memory() for non-TDX configs Jeremi Piotrowski
2023-11-23 14:11 ` Kirill A. Shutemov
2023-11-24 10:00 ` Jeremi Piotrowski
2023-11-22 17:19 ` Jeremi Piotrowski [this message]
2023-11-29 16:40 ` [PATCH v1 1/3] x86/tdx: Check for TDX partitioning during early TDX init Borislav Petkov
2023-11-30 7:08 ` Reshetova, Elena
2023-11-30 7:55 ` Borislav Petkov
2023-11-30 8:31 ` Reshetova, Elena
2023-11-30 9:21 ` Borislav Petkov
2023-12-04 16:44 ` Jeremi Piotrowski
2023-12-04 13:39 ` Jeremi Piotrowski
2023-12-04 19:37 ` Jeremi Piotrowski
2023-11-23 13:58 ` Kirill A. Shutemov
2023-11-24 10:31 ` Jeremi Piotrowski
2023-11-24 10:43 ` Kirill A. Shutemov
2023-11-24 11:04 ` Jeremi Piotrowski
2023-11-24 13:33 ` Kirill A. Shutemov
2023-11-24 16:19 ` Jeremi Piotrowski
2023-11-29 4:36 ` Huang, Kai
2023-12-01 16:16 ` Jeremi Piotrowski
2023-12-05 13:26 ` Huang, Kai
2023-12-06 18:47 ` Jeremi Piotrowski
2023-12-07 12:58 ` Huang, Kai
2023-12-07 17:21 ` Jeremi Piotrowski
2023-12-07 19:35 ` Jeremi Piotrowski
2023-12-08 10:51 ` Huang, Kai
2023-12-07 17:36 ` Reshetova, Elena
2023-12-08 12:45 ` Jeremi Piotrowski
2023-12-04 9:17 ` Reshetova, Elena
2023-12-04 19:07 ` Jeremi Piotrowski
2023-12-05 10:54 ` Kirill A. Shutemov
2023-12-06 17:49 ` Jeremi Piotrowski
2023-12-06 22:54 ` Kirill A. Shutemov
2023-12-07 17:06 ` Jeremi Piotrowski
2023-12-07 20:56 ` Kirill A. Shutemov
2023-12-05 13:24 ` Reshetova, Elena
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