Commit 7ae15e2f authored by Kiryl Shutsemau's avatar Kiryl Shutsemau Committed by Dave Hansen
Browse files

x86/tdx: Enable CPU topology enumeration 



TDX 1.0 defines baseline behaviour of TDX guest platform. TDX 1.0
generates a #VE when accessing topology-related CPUID leafs (0xB and
0x1F) and the X2APIC_APICID MSR. The kernel returns all zeros on CPUID
topology. In practice, this means that the kernel can only boot with a
plain topology. Any complications will cause problems.

The ENUM_TOPOLOGY feature allows the VMM to provide topology
information to the guest. Enabling the feature eliminates
topology-related #VEs: the TDX module virtualizes accesses to
the CPUID leafs and the MSR.

Enable ENUM_TOPOLOGY if it is available.

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Acked-by: default avatarKai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/all/20241104103803.195705-5-kirill.shutemov%40linux.intel.com
parent f65aa0ad

arch/x86/coco/tdx/tdx.c

+27 −0
Original line number Diff line number Diff line
@@ -248,6 +248,32 @@ static void disable_sept_ve(u64 td_attr) 
		  TD_CTLS_PENDING_VE_DISABLE);

}



/*

 * TDX 1.0 generates a #VE when accessing topology-related CPUID leafs (0xB and

 * 0x1F) and the X2APIC_APICID MSR. The kernel returns all zeros on CPUID #VEs.

 * In practice, this means that the kernel can only boot with a plain topology.

 * Any complications will cause problems.

 *

 * The ENUM_TOPOLOGY feature allows the VMM to provide topology information.

 * Enabling the feature  eliminates topology-related #VEs: the TDX module

 * virtualizes accesses to the CPUID leafs and the MSR.

 *

 * Enable ENUM_TOPOLOGY if it is available.

 */

static void enable_cpu_topology_enumeration(void)

{

	u64 configured;



	/* Has the VMM provided a valid topology configuration? */

	tdg_vm_rd(TDCS_TOPOLOGY_ENUM_CONFIGURED, &configured);

	if (!configured) {

		pr_err("VMM did not configure X2APIC_IDs properly\n");

		return;

	}



	tdg_vm_wr(TDCS_TD_CTLS, TD_CTLS_ENUM_TOPOLOGY, TD_CTLS_ENUM_TOPOLOGY);

}



static void tdx_setup(u64 *cc_mask)

{

	struct tdx_module_args args = {};
@@ -279,6 +305,7 @@ static void tdx_setup(u64 *cc_mask) 
	tdg_vm_wr(TDCS_NOTIFY_ENABLES, 0, -1ULL);



	disable_sept_ve(td_attr);

	enable_cpu_topology_enumeration();

}



/*

arch/x86/include/asm/shared/tdx.h

+2 −0
Original line number Diff line number Diff line
@@ -23,12 +23,14 @@ 
#define TDCS_CONFIG_FLAGS		0x1110000300000016

#define TDCS_TD_CTLS			0x1110000300000017

#define TDCS_NOTIFY_ENABLES		0x9100000000000010

#define TDCS_TOPOLOGY_ENUM_CONFIGURED	0x9100000000000019



/* TDCS_CONFIG_FLAGS bits */

#define TDCS_CONFIG_FLEXIBLE_PENDING_VE	BIT_ULL(1)



/* TDCS_TD_CTLS bits */

#define TD_CTLS_PENDING_VE_DISABLE	BIT_ULL(0)

#define TD_CTLS_ENUM_TOPOLOGY		BIT_ULL(1)



/* TDX hypercall Leaf IDs */

#define TDVMCALL_MAP_GPA		0x10001