Commit b8c3c9f5 authored by Neeraj Upadhyay's avatar Neeraj Upadhyay Committed by Borislav Petkov (AMD)
Browse files

x86/apic: Initialize Secure AVIC APIC backing page 



With Secure AVIC, the APIC backing page is owned and managed by the guest.
Allocate and initialize APIC backing page for all guest CPUs.

The NPT entry for a vCPU's APIC backing page must always be present when the
vCPU is running in order for Secure AVIC to function. A VMEXIT_BUSY is
returned on VMRUN and the vCPU cannot be resumed otherwise.

To handle this, notify GPA of the vCPU's APIC backing page to the hypervisor
by using the SVM_VMGEXIT_SECURE_AVIC GHCB protocol event. Before executing
VMRUN, the hypervisor makes use of this information to make sure the APIC
backing page is mapped in the NPT.

  [ bp: Massage commit message. ]

Co-developed-by: default avatarKishon Vijay Abraham I <kvijayab@amd.com>
Signed-off-by: default avatarKishon Vijay Abraham I <kvijayab@amd.com>
Signed-off-by: default avatarNeeraj Upadhyay <Neeraj.Upadhyay@amd.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: default avatarTianyu Lan <tiala@microsoft.com>
Link: https://lore.kernel.org/20250828070334.208401-3-Neeraj.Upadhyay@amd.com
parent 30c2b98a

arch/x86/coco/sev/core.c

+22 −0
Original line number Diff line number Diff line
@@ -1108,6 +1108,28 @@ int __init sev_es_efi_map_ghcbs_cas(pgd_t *pgd) 
	return 0;

}



enum es_result savic_register_gpa(u64 gpa)

{

	struct ghcb_state state;

	struct es_em_ctxt ctxt;

	enum es_result res;

	struct ghcb *ghcb;



	guard(irqsave)();



	ghcb = __sev_get_ghcb(&state);

	vc_ghcb_invalidate(ghcb);



	ghcb_set_rax(ghcb, SVM_VMGEXIT_SAVIC_SELF_GPA);

	ghcb_set_rbx(ghcb, gpa);

	res = sev_es_ghcb_hv_call(ghcb, &ctxt, SVM_VMGEXIT_SAVIC,

				  SVM_VMGEXIT_SAVIC_REGISTER_GPA, 0);



	__sev_put_ghcb(&state);



	return res;

}



static void snp_register_per_cpu_ghcb(void)

{

	struct sev_es_runtime_data *data;

arch/x86/include/asm/apic.h

+1 −0
Original line number Diff line number Diff line
@@ -305,6 +305,7 @@ struct apic { 


	/* Probe, setup and smpboot functions */

	int	(*probe)(void);

	void	(*setup)(void);

	int	(*acpi_madt_oem_check)(char *oem_id, char *oem_table_id);



	void	(*init_apic_ldr)(void);

arch/x86/include/asm/sev.h

+2 −0
Original line number Diff line number Diff line
@@ -533,6 +533,7 @@ int snp_svsm_vtpm_send_command(u8 *buffer); 


void __init snp_secure_tsc_prepare(void);

void __init snp_secure_tsc_init(void);

enum es_result savic_register_gpa(u64 gpa);



static __always_inline void vc_ghcb_invalidate(struct ghcb *ghcb)

{
@@ -605,6 +606,7 @@ static inline int snp_send_guest_request(struct snp_msg_desc *mdesc, 
static inline int snp_svsm_vtpm_send_command(u8 *buffer) { return -ENODEV; }

static inline void __init snp_secure_tsc_prepare(void) { }

static inline void __init snp_secure_tsc_init(void) { }

static inline enum es_result savic_register_gpa(u64 gpa) { return ES_UNSUPPORTED; }



#endif	/* CONFIG_AMD_MEM_ENCRYPT */

arch/x86/include/uapi/asm/svm.h

+4 −0
Original line number Diff line number Diff line
@@ -118,6 +118,10 @@ 
#define SVM_VMGEXIT_AP_CREATE			1

#define SVM_VMGEXIT_AP_DESTROY			2

#define SVM_VMGEXIT_SNP_RUN_VMPL		0x80000018

#define SVM_VMGEXIT_SAVIC			0x8000001a

#define SVM_VMGEXIT_SAVIC_REGISTER_GPA		0

#define SVM_VMGEXIT_SAVIC_UNREGISTER_GPA	1

#define SVM_VMGEXIT_SAVIC_SELF_GPA		~0ULL

#define SVM_VMGEXIT_HV_FEATURES			0x8000fffd

#define SVM_VMGEXIT_TERM_REQUEST		0x8000fffe

#define SVM_VMGEXIT_TERM_REASON(reason_set, reason_code)	\

arch/x86/kernel/apic/apic.c

+3 −0
Original line number Diff line number Diff line
@@ -1501,6 +1501,9 @@ static void setup_local_APIC(void) 
		return;

	}



	if (apic->setup)

		apic->setup();



	/*

	 * If this comes from kexec/kcrash the APIC might be enabled in

	 * SPIV. Soft disable it before doing further initialization.