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SubjectRe: [PATCH] KVM: VMX: Use wrapper macro ~RMODE_GUEST_OWNED_EFLAGS_BITS directly
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linmiaohe <linmiaohe@huawei.com> writes:

> From: Miaohe Lin <linmiaohe@huawei.com>
>
> (X86_EFLAGS_IOPL | X86_EFLAGS_VM) indicates the eflag bits that can not be
> owned by realmode guest, i.e. ~RMODE_GUEST_OWNED_EFLAGS_BITS. Use wrapper
> macro directly to make it clear and also improve readability.
>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
> arch/x86/kvm/vmx/vmx.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 743b81642ce2..9571f8dea016 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -1466,7 +1466,7 @@ void vmx_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags)
> vmx->rflags = rflags;
> if (vmx->rmode.vm86_active) {
> vmx->rmode.save_rflags = rflags;
> - rflags |= X86_EFLAGS_IOPL | X86_EFLAGS_VM;
> + rflags |= ~RMODE_GUEST_OWNED_EFLAGS_BITS;
> }
> vmcs_writel(GUEST_RFLAGS, rflags);
>
> @@ -2797,7 +2797,7 @@ static void enter_rmode(struct kvm_vcpu *vcpu)
> flags = vmcs_readl(GUEST_RFLAGS);
> vmx->rmode.save_rflags = flags;
>
> - flags |= X86_EFLAGS_IOPL | X86_EFLAGS_VM;
> + flags |= ~RMODE_GUEST_OWNED_EFLAGS_BITS;
>
> vmcs_writel(GUEST_RFLAGS, flags);
> vmcs_writel(GUEST_CR4, vmcs_readl(GUEST_CR4) | X86_CR4_VME);

Double negations are evil, let's define a macro for 'X86_EFLAGS_IOPL |
X86_EFLAGS_VM' instead (completely untested):

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 4ee19fb35cde..d838f93bd6d2 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -139,7 +139,8 @@ module_param_named(preemption_timer, enable_preemption_timer, bool, S_IRUGO);
#define KVM_PMODE_VM_CR4_ALWAYS_ON (X86_CR4_PAE | X86_CR4_VMXE)
#define KVM_RMODE_VM_CR4_ALWAYS_ON (X86_CR4_VME | X86_CR4_PAE | X86_CR4_VMXE)

-#define RMODE_GUEST_OWNED_EFLAGS_BITS (~(X86_EFLAGS_IOPL | X86_EFLAGS_VM))
+#define RMODE_HOST_OWNED_EFLAGS_BITS (X86_EFLAGS_IOPL | X86_EFLAGS_VM)
+#define RMODE_GUEST_OWNED_EFLAGS_BITS (~RMODE_HOST_OWNED_EFLAGS_BITS)

#define MSR_IA32_RTIT_STATUS_MASK (~(RTIT_STATUS_FILTEREN | \
RTIT_STATUS_CONTEXTEN | RTIT_STATUS_TRIGGEREN | \
@@ -1468,7 +1469,7 @@ void vmx_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags)
vmx->rflags = rflags;
if (vmx->rmode.vm86_active) {
vmx->rmode.save_rflags = rflags;
- rflags |= X86_EFLAGS_IOPL | X86_EFLAGS_VM;
+ rflags |= RMODE_HOST_OWNED_EFLAGS_BITS;
}
vmcs_writel(GUEST_RFLAGS, rflags);

@@ -2794,7 +2795,7 @@ static void enter_rmode(struct kvm_vcpu *vcpu)
flags = vmcs_readl(GUEST_RFLAGS);
vmx->rmode.save_rflags = flags;

- flags |= X86_EFLAGS_IOPL | X86_EFLAGS_VM;
+ flags |= RMODE_HOST_OWNED_EFLAGS_BITS;

vmcs_writel(GUEST_RFLAGS, flags);
vmcs_writel(GUEST_CR4, vmcs_readl(GUEST_CR4) | X86_CR4_VME);
--
Vitaly

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