Commit a21d1bec authored by Srikar Dronamraju's avatar Srikar Dronamraju Committed by Michael Ellerman
Browse files

powerpc: Reintroduce is_kvm_guest() as a fast-path check 



Introduce a static branch that would be set during boot if the OS
happens to be a KVM guest. Subsequent checks to see if we are on KVM
will rely on this static branch. This static branch would be used in
vcpu_is_preempted() in a subsequent patch.

Signed-off-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201202050456.164005-4-srikar@linux.vnet.ibm.com
parent 16520a85

arch/powerpc/include/asm/kvm_guest.h

+10 −0
Original line number Diff line number Diff line
@@ -7,8 +7,18 @@ 
#define _ASM_POWERPC_KVM_GUEST_H_



#if defined(CONFIG_PPC_PSERIES) || defined(CONFIG_KVM_GUEST)

#include <linux/jump_label.h>



DECLARE_STATIC_KEY_FALSE(kvm_guest);



static inline bool is_kvm_guest(void)

{

	return static_branch_unlikely(&kvm_guest);

}



bool check_kvm_guest(void);

#else

static inline bool is_kvm_guest(void) { return false; }

static inline bool check_kvm_guest(void) { return false; }

#endif

arch/powerpc/include/asm/kvm_para.h

+1 −1
Original line number Diff line number Diff line
@@ -14,7 +14,7 @@ 


static inline int kvm_para_available(void)

{

	return IS_ENABLED(CONFIG_KVM_GUEST) && check_kvm_guest();

	return IS_ENABLED(CONFIG_KVM_GUEST) && is_kvm_guest();

}



static inline unsigned int kvm_arch_para_features(void)

arch/powerpc/kernel/firmware.c

+2 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ EXPORT_SYMBOL_GPL(powerpc_firmware_features); 
#endif



#if defined(CONFIG_PPC_PSERIES) || defined(CONFIG_KVM_GUEST)

DEFINE_STATIC_KEY_FALSE(kvm_guest);

bool check_kvm_guest(void)

{

	struct device_node *hyper_node;
@@ -33,6 +34,7 @@ bool check_kvm_guest(void) 
	if (!of_device_is_compatible(hyper_node, "linux,kvm"))

		return false;



	static_branch_enable(&kvm_guest);

	return true;

}

#endif