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Date: Fri, 25 Sep 2020 22:21:33 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: Sean Christopherson <sean.j.christopherson@...el.com>
Cc: Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/4] KVM: VMX: Add a helper and macros to reduce
boilerplate for sec exec ctls
On 25/09/20 02:30, Sean Christopherson wrote:
> Add a helper function and several wrapping macros to consolidate the
> copy-paste code in vmx_compute_secondary_exec_control() for adjusting
> controls that are dependent on guest CPUID bits.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> ---
>
> v2: Comment the new helper and macros.
>
> arch/x86/kvm/vmx/vmx.c | 151 +++++++++++++++++------------------------
> 1 file changed, 64 insertions(+), 87 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 5180529f6531..48673eea0c0d 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -4072,6 +4072,61 @@ u32 vmx_exec_control(struct vcpu_vmx *vmx)
> return exec_control;
> }
>
> +/*
> + * Adjust a single secondary execution control bit to intercept/allow an
> + * instruction in the guest. This is usually done based on whether or not a
> + * feature has been exposed to the guest in order to correctly emulate faults.
> + */
> +static inline void
> +vmx_adjust_secondary_exec_control(struct vcpu_vmx *vmx, u32 *exec_control,
> + u32 control, bool enabled, bool exiting)
> +{
> + /*
> + * If the control is for an opt-in feature, clear the control if the
> + * feature is not exposed to the guest, i.e. not enabled. If the
> + * control is opt-out, i.e. an exiting control, clear the control if
> + * the feature _is_ exposed to the guest, i.e. exiting/interception is
> + * disabled for the associated instruction. Note, the caller is
> + * responsible presetting exec_control to set all supported bits.
> + */
> + if (enabled == exiting)
> + *exec_control &= ~control;
> +
> + /*
> + * Update the nested MSR settings so that a nested VMM can/can't set
> + * controls for features that are/aren't exposed to the guest.
> + */
> + if (nested) {
> + if (enabled)
> + vmx->nested.msrs.secondary_ctls_high |= control;
> + else
> + vmx->nested.msrs.secondary_ctls_high &= ~control;
> + }
> +}
> +
> +/*
> + * Wrapper macro for the common case of adjusting a secondary execution control
> + * based on a single guest CPUID bit, with a dedicated feature bit. This also
> + * verifies that the control is actually supported by KVM and hardware.
> + */
> +#define vmx_adjust_sec_exec_control(vmx, exec_control, name, feat_name, ctrl_name, exiting) \
> +({ \
> + bool __enabled; \
> + \
> + if (cpu_has_vmx_##name()) { \
> + __enabled = guest_cpuid_has(&(vmx)->vcpu, \
> + X86_FEATURE_##feat_name); \
> + vmx_adjust_secondary_exec_control(vmx, exec_control, \
> + SECONDARY_EXEC_##ctrl_name, __enabled, exiting); \
> + } \
> +})
> +
> +/* More macro magic for ENABLE_/opt-in versus _EXITING/opt-out controls. */
> +#define vmx_adjust_sec_exec_feature(vmx, exec_control, lname, uname) \
> + vmx_adjust_sec_exec_control(vmx, exec_control, lname, uname, ENABLE_##uname, false)
> +
> +#define vmx_adjust_sec_exec_exiting(vmx, exec_control, lname, uname) \
> + vmx_adjust_sec_exec_control(vmx, exec_control, lname, uname, uname##_EXITING, true)
>
> static void vmx_compute_secondary_exec_control(struct vcpu_vmx *vmx)
> {
> @@ -4121,33 +4176,12 @@ static void vmx_compute_secondary_exec_control(struct vcpu_vmx *vmx)
>
> vcpu->arch.xsaves_enabled = xsaves_enabled;
>
> - if (!xsaves_enabled)
> - exec_control &= ~SECONDARY_EXEC_XSAVES;
> -
> - if (nested) {
> - if (xsaves_enabled)
> - vmx->nested.msrs.secondary_ctls_high |=
> - SECONDARY_EXEC_XSAVES;
> - else
> - vmx->nested.msrs.secondary_ctls_high &=
> - ~SECONDARY_EXEC_XSAVES;
> - }
> + vmx_adjust_secondary_exec_control(vmx, &exec_control,
> + SECONDARY_EXEC_XSAVES,
> + xsaves_enabled, false);
> }
>
> - if (cpu_has_vmx_rdtscp()) {
> - bool rdtscp_enabled = guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP);
> - if (!rdtscp_enabled)
> - exec_control &= ~SECONDARY_EXEC_ENABLE_RDTSCP;
> -
> - if (nested) {
> - if (rdtscp_enabled)
> - vmx->nested.msrs.secondary_ctls_high |=
> - SECONDARY_EXEC_ENABLE_RDTSCP;
> - else
> - vmx->nested.msrs.secondary_ctls_high &=
> - ~SECONDARY_EXEC_ENABLE_RDTSCP;
> - }
> - }
> + vmx_adjust_sec_exec_feature(vmx, &exec_control, rdtscp, RDTSCP);
>
> /*
> * Expose INVPCID if and only if PCID is also exposed to the guest.
> @@ -4157,71 +4191,14 @@ static void vmx_compute_secondary_exec_control(struct vcpu_vmx *vmx)
> */
> if (!guest_cpuid_has(vcpu, X86_FEATURE_PCID))
> guest_cpuid_clear(vcpu, X86_FEATURE_INVPCID);
> + vmx_adjust_sec_exec_feature(vmx, &exec_control, invpcid, INVPCID);
>
> - if (cpu_has_vmx_invpcid()) {
> - /* Exposing INVPCID only when PCID is exposed */
> - bool invpcid_enabled =
> - guest_cpuid_has(vcpu, X86_FEATURE_INVPCID);
>
> - if (!invpcid_enabled)
> - exec_control &= ~SECONDARY_EXEC_ENABLE_INVPCID;
> + vmx_adjust_sec_exec_exiting(vmx, &exec_control, rdrand, RDRAND);
> + vmx_adjust_sec_exec_exiting(vmx, &exec_control, rdseed, RDSEED);
>
> - if (nested) {
> - if (invpcid_enabled)
> - vmx->nested.msrs.secondary_ctls_high |=
> - SECONDARY_EXEC_ENABLE_INVPCID;
> - else
> - vmx->nested.msrs.secondary_ctls_high &=
> - ~SECONDARY_EXEC_ENABLE_INVPCID;
> - }
> - }
> -
> - if (cpu_has_vmx_rdrand()) {
> - bool rdrand_enabled = guest_cpuid_has(vcpu, X86_FEATURE_RDRAND);
> - if (rdrand_enabled)
> - exec_control &= ~SECONDARY_EXEC_RDRAND_EXITING;
> -
> - if (nested) {
> - if (rdrand_enabled)
> - vmx->nested.msrs.secondary_ctls_high |=
> - SECONDARY_EXEC_RDRAND_EXITING;
> - else
> - vmx->nested.msrs.secondary_ctls_high &=
> - ~SECONDARY_EXEC_RDRAND_EXITING;
> - }
> - }
> -
> - if (cpu_has_vmx_rdseed()) {
> - bool rdseed_enabled = guest_cpuid_has(vcpu, X86_FEATURE_RDSEED);
> - if (rdseed_enabled)
> - exec_control &= ~SECONDARY_EXEC_RDSEED_EXITING;
> -
> - if (nested) {
> - if (rdseed_enabled)
> - vmx->nested.msrs.secondary_ctls_high |=
> - SECONDARY_EXEC_RDSEED_EXITING;
> - else
> - vmx->nested.msrs.secondary_ctls_high &=
> - ~SECONDARY_EXEC_RDSEED_EXITING;
> - }
> - }
> -
> - if (cpu_has_vmx_waitpkg()) {
> - bool waitpkg_enabled =
> - guest_cpuid_has(vcpu, X86_FEATURE_WAITPKG);
> -
> - if (!waitpkg_enabled)
> - exec_control &= ~SECONDARY_EXEC_ENABLE_USR_WAIT_PAUSE;
> -
> - if (nested) {
> - if (waitpkg_enabled)
> - vmx->nested.msrs.secondary_ctls_high |=
> - SECONDARY_EXEC_ENABLE_USR_WAIT_PAUSE;
> - else
> - vmx->nested.msrs.secondary_ctls_high &=
> - ~SECONDARY_EXEC_ENABLE_USR_WAIT_PAUSE;
> - }
> - }
> + vmx_adjust_sec_exec_control(vmx, &exec_control, waitpkg, WAITPKG,
> + ENABLE_USR_WAIT_PAUSE, false);
>
> vmx->secondary_exec_control = exec_control;
> }
>
Queued with the rest, thanks.
Paolo
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