Commit 1e0cf16c authored by Marc Zyngier's avatar Marc Zyngier
Browse files

KVM: arm/arm64: Initialise host's MPIDRs by reading the actual register 



As part of setting up the host context, we populate its
MPIDR by using cpu_logical_map(). It turns out that contrary
to arm64, cpu_logical_map() on 32bit ARM doesn't return the
*full* MPIDR, but a truncated version.

This leaves the host MPIDR slightly corrupted after the first
run of a VM, since we won't correctly restore the MPIDR on
exit. Oops.

Since we cannot trust cpu_logical_map(), let's adopt a different
strategy. We move the initialization of the host CPU context as
part of the per-CPU initialization (which, in retrospect, makes
a lot of sense), and directly read the MPIDR from the HW. This
is guaranteed to work on both arm and arm64.

Reported-by: default avatarAndre Przywara <Andre.Przywara@arm.com>
Tested-by: default avatarAndre Przywara <Andre.Przywara@arm.com>
Fixes: 32f13955 ("arm/arm64: KVM: Statically configure the host's view of MPIDR")
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent fdec2a9e

arch/arm/include/asm/kvm_host.h

+2 −4
Original line number Diff line number Diff line
@@ -15,7 +15,6 @@ 
#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
@@ -147,11 +146,10 @@ struct kvm_host_data { 


typedef struct kvm_host_data kvm_host_data_t;



static inline void kvm_init_host_cpu_context(struct kvm_cpu_context *cpu_ctxt,

					     int cpu)

static inline void kvm_init_host_cpu_context(struct kvm_cpu_context *cpu_ctxt)

{

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

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

	cpu_ctxt->cp15[c0_MPIDR] = read_cpuid_mpidr();

}



struct vcpu_reset_state {

arch/arm64/include/asm/kvm_host.h

+3 −4
Original line number Diff line number Diff line
@@ -19,12 +19,12 @@ 
#include <asm/arch_gicv3.h>

#include <asm/barrier.h>

#include <asm/cpufeature.h>

#include <asm/cputype.h>

#include <asm/daifflags.h>

#include <asm/fpsimd.h>

#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
@@ -484,11 +484,10 @@ struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr); 


DECLARE_PER_CPU(kvm_host_data_t, kvm_host_data);



static inline void kvm_init_host_cpu_context(struct kvm_cpu_context *cpu_ctxt,

					     int cpu)

static inline void kvm_init_host_cpu_context(struct kvm_cpu_context *cpu_ctxt)

{

	/* 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);

	cpu_ctxt->sys_regs[MPIDR_EL1] = read_cpuid_mpidr();

}



void __kvm_enable_ssbs(void);

virt/kvm/arm/arm.c

+2 −1
Original line number Diff line number Diff line
@@ -1332,6 +1332,8 @@ static void cpu_hyp_reset(void) 


static void cpu_hyp_reinit(void)

{

	kvm_init_host_cpu_context(&this_cpu_ptr(&kvm_host_data)->host_ctxt);



	cpu_hyp_reset();



	if (is_kernel_in_hyp_mode())
@@ -1569,7 +1571,6 @@ static int init_hyp_mode(void) 
		kvm_host_data_t *cpu_data;



		cpu_data = per_cpu_ptr(&kvm_host_data, cpu);

		kvm_init_host_cpu_context(&cpu_data->host_ctxt, cpu);

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



		if (err) {