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KVM: x86: Add support for vICR APIC-write VM-Exits in x2APIC mode

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Upcoming Intel CPUs will support virtual x2APIC MSR writes to the vICR,
i.e. will trap and generate an APIC-write VM-Exit instead of intercepting
the WRMSR.  Add support for handling "nodecode" x2APIC writes, which
were previously impossible.

Note, x2APIC MSR writes are 64 bits wide.

Signed-off-by: Zeng Guang <guang.zeng@intel.com>
Message-Id: <20220419153516.11739-1-guang.zeng@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Zeng Guang 2022-04-19 23:35:16 +08:00 committed by Paolo Bonzini
parent 0b85baa5f4
commit 5413bcba7e
1 changed files with 21 additions and 3 deletions
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24
arch/x86/kvm/lapic.c
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@ -67,6 +67,7 @@ static bool lapic_timer_advance_dynamic __read_mostly;
#define LAPIC_TIMER_ADVANCE_NS_MAX 5000
/* step-by-step approximation to mitigate fluctuation */
#define LAPIC_TIMER_ADVANCE_ADJUST_STEP 8
static int kvm_lapic_msr_read(struct kvm_lapic *apic, u32 reg, u64 *data);
static inline void __kvm_lapic_set_reg(char *regs, int reg_off, u32 val)
{
@ -2231,10 +2232,27 @@ EXPORT_SYMBOL_GPL(kvm_lapic_set_eoi);
/* emulate APIC access in a trap manner */
void kvm_apic_write_nodecode(struct kvm_vcpu *vcpu, u32 offset)
{
u32 val = kvm_lapic_get_reg(vcpu->arch.apic, offset);
struct kvm_lapic *apic = vcpu->arch.apic;
u64 val;
/* TODO: optimize to just emulate side effect w/o one more write */
kvm_lapic_reg_write(vcpu->arch.apic, offset, val);
if (apic_x2apic_mode(apic)) {
/*
* When guest APIC is in x2APIC mode and IPI virtualization
* is enabled, accessing APIC_ICR may cause trap-like VM-exit
* on Intel hardware. Other offsets are not possible.
*/
if (WARN_ON_ONCE(offset != APIC_ICR))
return;
kvm_lapic_msr_read(apic, offset, &val);
kvm_apic_send_ipi(apic, (u32)val, (u32)(val >> 32));
trace_kvm_apic_write(APIC_ICR, val);
} else {
val = kvm_lapic_get_reg(apic, offset);
/* TODO: optimize to just emulate side effect w/o one more write */
kvm_lapic_reg_write(apic, offset, (u32)val);
}
}
EXPORT_SYMBOL_GPL(kvm_apic_write_nodecode);