On 16/08/2017 03:58, Lan Tianyu wrote:
> These CR3 VMEXITs was introduced for platform without "unrestricted guest"
> support. This is to set ept identity table to guest CR3 in guest real
> mode because these platforms don't support ept real mode(CR0.PE and CR0.PG
> must be set to 1). But these VMEXITs is redundant for platforms with
> "unrestricted guest" support.
This is true, but I'm not sure it's a good idea to make things more
complex... It is working code and is not a bottleneck anywhere.
Paolo
> Signed-off-by: Lan Tianyu <tianyu.lan@xxxxxxxxx>
> ---
> arch/x86/kvm/vmx.c | 22 +++++++++++++---------
> 1 file changed, 13 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 9b21b12..46dcf50 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -4221,18 +4221,20 @@ static void ept_update_paging_mode_cr0(unsigned long *hw_cr0,
> vmx_decache_cr3(vcpu);
> if (!(cr0 & X86_CR0_PG)) {
> /* From paging/starting to nonpaging */
> - vmcs_write32(CPU_BASED_VM_EXEC_CONTROL,
> - vmcs_read32(CPU_BASED_VM_EXEC_CONTROL) |
> - (CPU_BASED_CR3_LOAD_EXITING |
> - CPU_BASED_CR3_STORE_EXITING));
> + if (!enable_unrestricted_guest)
> + vmcs_write32(CPU_BASED_VM_EXEC_CONTROL,
> + vmcs_read32(CPU_BASED_VM_EXEC_CONTROL) |
> + (CPU_BASED_CR3_LOAD_EXITING |
> + CPU_BASED_CR3_STORE_EXITING));
> vcpu->arch.cr0 = cr0;
> vmx_set_cr4(vcpu, kvm_read_cr4(vcpu));
> } else if (!is_paging(vcpu)) {
> /* From nonpaging to paging */
> - vmcs_write32(CPU_BASED_VM_EXEC_CONTROL,
> - vmcs_read32(CPU_BASED_VM_EXEC_CONTROL) &
> - ~(CPU_BASED_CR3_LOAD_EXITING |
> - CPU_BASED_CR3_STORE_EXITING));
> + if (!enable_unrestricted_guest)
> + vmcs_write32(CPU_BASED_VM_EXEC_CONTROL,
> + vmcs_read32(CPU_BASED_VM_EXEC_CONTROL) &
> + ~(CPU_BASED_CR3_LOAD_EXITING |
> + CPU_BASED_CR3_STORE_EXITING));
> vcpu->arch.cr0 = cr0;
> vmx_set_cr4(vcpu, kvm_read_cr4(vcpu));
> }
> @@ -4311,7 +4313,9 @@ static void vmx_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
> }
>
> vmx_flush_tlb(vcpu);
> - vmcs_writel(GUEST_CR3, guest_cr3);
> +
> + if (!enable_unrestricted_guest || !enable_ept)
> + vmcs_writel(GUEST_CR3, guest_cr3);
> }
>
> static int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
>
