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

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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: Andre Przywara <Andre.Przywara@arm.com>
Tested-by: Andre Przywara <Andre.Przywara@arm.com>
Fixes: 32f1395519 ("arm/arm64: KVM: Statically configure the host's view of MPIDR")
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Marc Zyngier
2019-07-05 23:35:56 +01:00
parent fdec2a9ef8
commit 1e0cf16cda
3 changed files with 7 additions and 9 deletions
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7
arch/arm64/include/asm/kvm_host.h
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@@ -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);