On 02/03/20 20:57, Sean Christopherson wrote:
> Add a helper to retrieve cpuid_maxphyaddr() instead of manually
> calculating the value in the emulator via raw CPUID output. In addition
> to consolidating logic, this also paves the way toward simplifying
> kvm_cpuid(), whose somewhat confusing return value exists purely to
> support the emulator's maxphyaddr calculation.
>
> No functional change intended.
I don't think this is a particularly useful change. Yes, it's not
intuitive but is it more than a matter of documentation (and possibly
moving the check_cr_write snippet into a separate function)?
Paolo
> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> ---
> arch/x86/include/asm/kvm_emulate.h | 1 +
> arch/x86/kvm/emulate.c | 10 +---------
> arch/x86/kvm/x86.c | 6 ++++++
> 3 files changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
> index bf5f5e476f65..ded06515d30f 100644
> --- a/arch/x86/include/asm/kvm_emulate.h
> +++ b/arch/x86/include/asm/kvm_emulate.h
> @@ -222,6 +222,7 @@ struct x86_emulate_ops {
>
> bool (*get_cpuid)(struct x86_emulate_ctxt *ctxt, u32 *eax, u32 *ebx,
> u32 *ecx, u32 *edx, bool check_limit);
> + int (*get_cpuid_maxphyaddr)(struct x86_emulate_ctxt *ctxt);
> bool (*guest_has_long_mode)(struct x86_emulate_ctxt *ctxt);
> bool (*guest_has_movbe)(struct x86_emulate_ctxt *ctxt);
> bool (*guest_has_fxsr)(struct x86_emulate_ctxt *ctxt);
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index dd19fb3539e0..bf02ed51e90f 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -4244,16 +4244,8 @@ static int check_cr_write(struct x86_emulate_ctxt *ctxt)
>
> ctxt->ops->get_msr(ctxt, MSR_EFER, &efer);
> if (efer & EFER_LMA) {
> - u64 maxphyaddr;
> - u32 eax, ebx, ecx, edx;
> + int maxphyaddr = ctxt->ops->get_cpuid_maxphyaddr(ctxt);
>
> - eax = 0x80000008;
> - ecx = 0;
> - if (ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx,
> - &edx, false))
> - maxphyaddr = eax & 0xff;
> - else
> - maxphyaddr = 36;
> rsvd = rsvd_bits(maxphyaddr, 63);
> if (ctxt->ops->get_cr(ctxt, 4) & X86_CR4_PCIDE)
> rsvd &= ~X86_CR3_PCID_NOFLUSH;
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index ddd1d296bd20..5467ee71c25b 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6209,6 +6209,11 @@ static bool emulator_get_cpuid(struct x86_emulate_ctxt *ctxt,
> return kvm_cpuid(emul_to_vcpu(ctxt), eax, ebx, ecx, edx, check_limit);
> }
>
> +static int emulator_get_cpuid_maxphyaddr(struct x86_emulate_ctxt *ctxt)
> +{
> + return cpuid_maxphyaddr(emul_to_vcpu(ctxt));
> +}
> +
> static bool emulator_guest_has_long_mode(struct x86_emulate_ctxt *ctxt)
> {
> return guest_cpuid_has(emul_to_vcpu(ctxt), X86_FEATURE_LM);
> @@ -6301,6 +6306,7 @@ static const struct x86_emulate_ops emulate_ops = {
> .fix_hypercall = emulator_fix_hypercall,
> .intercept = emulator_intercept,
> .get_cpuid = emulator_get_cpuid,
> + .get_cpuid_maxphyaddr= emulator_get_cpuid_maxphyaddr,
> .guest_has_long_mode = emulator_guest_has_long_mode,
> .guest_has_movbe = emulator_guest_has_movbe,
> .guest_has_fxsr = emulator_guest_has_fxsr,
>
