Commit 32f13955 authored by Marc Zyngier's avatar Marc Zyngier
Browse files

arm/arm64: KVM: Statically configure the host's view of MPIDR 



We currently eagerly save/restore MPIDR. It turns out to be
slightly pointless:
- On the host, this value is known as soon as we're scheduled on a
  physical CPU
- In the guest, this value cannot change, as it is set by KVM
  (and this is a read-only register)

The result of the above is that we can perfectly avoid the eager
saving of MPIDR_EL1, and only keep the restore. We just have
to setup the host contexts appropriately at boot time.

Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Acked-by: default avatarChristoffer Dall <christoffer.dall@arm.com>
Signed-off-by: default avatarChristoffer Dall <christoffer.dall@arm.com>
parent d18232ea

arch/arm/include/asm/kvm_host.h

+8 −0
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
#include <asm/kvm_asm.h>

#include <asm/kvm_mmio.h>

#include <asm/fpstate.h>

#include <asm/smp_plat.h>

#include <kvm/arm_arch_timer.h>



#define __KVM_HAVE_ARCH_INTC_INITIALIZED
@@ -147,6 +148,13 @@ struct kvm_cpu_context { 


typedef struct kvm_cpu_context kvm_cpu_context_t;



static inline void kvm_init_host_cpu_context(kvm_cpu_context_t *cpu_ctxt,

					     int cpu)

{

	/* The host's MPIDR is immutable, so let's set it up at boot time */

	cpu_ctxt->cp15[c0_MPIDR] = cpu_logical_map(cpu);

}



struct kvm_vcpu_arch {

	struct kvm_cpu_context ctxt;

arch/arm/kvm/hyp/cp15-sr.c

+0 −1
Original line number Diff line number Diff line
@@ -27,7 +27,6 @@ static u64 *cp15_64(struct kvm_cpu_context *ctxt, int idx) 


void __hyp_text __sysreg_save_state(struct kvm_cpu_context *ctxt)

{

	ctxt->cp15[c0_MPIDR]		= read_sysreg(VMPIDR);

	ctxt->cp15[c0_CSSELR]		= read_sysreg(CSSELR);

	ctxt->cp15[c1_SCTLR]		= read_sysreg(SCTLR);

	ctxt->cp15[c1_CPACR]		= read_sysreg(CPACR);

arch/arm64/include/asm/kvm_host.h

+8 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ 
#include <asm/kvm.h>

#include <asm/kvm_asm.h>

#include <asm/kvm_mmio.h>

#include <asm/smp_plat.h>

#include <asm/thread_info.h>



#define __KVM_HAVE_ARCH_INTC_INITIALIZED
@@ -418,6 +419,13 @@ struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr); 


DECLARE_PER_CPU(kvm_cpu_context_t, kvm_host_cpu_state);



static inline void kvm_init_host_cpu_context(kvm_cpu_context_t *cpu_ctxt,

					     int cpu)

{

	/* The host's MPIDR is immutable, so let's set it up at boot time */

	cpu_ctxt->sys_regs[MPIDR_EL1] = cpu_logical_map(cpu);

}



void __kvm_enable_ssbs(void);



static inline void __cpu_init_hyp_mode(phys_addr_t pgd_ptr,

arch/arm64/kvm/hyp/sysreg-sr.c

+0 −1
Original line number Diff line number Diff line
@@ -52,7 +52,6 @@ static void __hyp_text __sysreg_save_user_state(struct kvm_cpu_context *ctxt) 


static void __hyp_text __sysreg_save_el1_state(struct kvm_cpu_context *ctxt)

{

	ctxt->sys_regs[MPIDR_EL1]	= read_sysreg(vmpidr_el2);

	ctxt->sys_regs[CSSELR_EL1]	= read_sysreg(csselr_el1);

	ctxt->sys_regs[SCTLR_EL1]	= read_sysreg_el1(sctlr);

	ctxt->sys_regs[ACTLR_EL1]	= read_sysreg(actlr_el1);

virt/kvm/arm/arm.c

+1 −0
Original line number Diff line number Diff line
@@ -1561,6 +1561,7 @@ static int init_hyp_mode(void) 
		kvm_cpu_context_t *cpu_ctxt;



		cpu_ctxt = per_cpu_ptr(&kvm_host_cpu_state, cpu);

		kvm_init_host_cpu_context(cpu_ctxt, cpu);

		err = create_hyp_mappings(cpu_ctxt, cpu_ctxt + 1, PAGE_HYP);



		if (err) {

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