Re: [PATCH 11/14] KVM: nVMX: hyper-v: Introduce nested_vmx_evmptr12() and nested_vmx_is_evmptr12_valid() helpers

From: Maxim Levitsky
Date: Tue Nov 07 2023 - 13:27:03 EST

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On Wed, 2023-10-25 at 17:24 +0200, Vitaly Kuznetsov wrote:
> 'vmx->nested.hv_evmcs_vmptr' accesses are all over the place so hiding
> 'hv_evmcs_vmptr' under 'ifdef CONFIG_KVM_HYPERV' would take a lot of
> ifdefs. Introduce 'nested_vmx_evmptr12()' accessor and
> 'nested_vmx_is_evmptr12_valid()' checker instead. Note, several explicit
>
> nested_vmx_evmptr12(vmx) != EVMPTR_INVALID
>
> comparisons exist for a reson: 'nested_vmx_is_evmptr12_valid()' also checks
> against 'EVMPTR_MAP_PENDING' and in these places this is undesireable. It
> is possible to e.g. introduce 'nested_vmx_is_evmptr12_invalid()' and turn
> these sites into
>
> !nested_vmx_is_evmptr12_invalid(vmx)
>
> eliminating the need for 'nested_vmx_evmptr12()' but this seems to create
> even more confusion.
Makes sense.
>
> No functional change intended.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> ---
> arch/x86/kvm/vmx/hyperv.h | 10 +++++++++
> arch/x86/kvm/vmx/nested.c | 44 +++++++++++++++++++--------------------
> arch/x86/kvm/vmx/nested.h | 2 +-
> 3 files changed, 33 insertions(+), 23 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/hyperv.h b/arch/x86/kvm/vmx/hyperv.h
> index 933ef6cad5e6..ba1a95ea72b7 100644
> --- a/arch/x86/kvm/vmx/hyperv.h
> +++ b/arch/x86/kvm/vmx/hyperv.h
> @@ -4,6 +4,7 @@
>
> #include <linux/kvm_host.h>
> #include "vmcs12.h"
> +#include "vmx.h"
>
> #define EVMPTR_INVALID (-1ULL)
> #define EVMPTR_MAP_PENDING (-2ULL)
> @@ -20,7 +21,14 @@ enum nested_evmptrld_status {
> EVMPTRLD_ERROR,
> };
>
> +struct vcpu_vmx;
> +
> #ifdef CONFIG_KVM_HYPERV
> +static inline gpa_t nested_vmx_evmptr12(struct vcpu_vmx *vmx) { return vmx->nested.hv_evmcs_vmptr; }
> +static inline bool nested_vmx_is_evmptr12_valid(struct vcpu_vmx *vmx)
> +{
> + return evmptr_is_valid(vmx->nested.hv_evmcs_vmptr);
> +}
> u64 nested_get_evmptr(struct kvm_vcpu *vcpu);
> uint16_t nested_get_evmcs_version(struct kvm_vcpu *vcpu);
> int nested_enable_evmcs(struct kvm_vcpu *vcpu,
> @@ -30,6 +38,8 @@ int nested_evmcs_check_controls(struct vmcs12 *vmcs12);
> bool nested_evmcs_l2_tlb_flush_enabled(struct kvm_vcpu *vcpu);
> void vmx_hv_inject_synthetic_vmexit_post_tlb_flush(struct kvm_vcpu *vcpu);
> #else
> +static inline gpa_t nested_vmx_evmptr12(struct vcpu_vmx *vmx) { return EVMPTR_INVALID; }
> +static inline bool nested_vmx_is_evmptr12_valid(struct vcpu_vmx *vmx) { return false; }
> static inline u64 nested_get_evmptr(struct kvm_vcpu *vcpu) { return EVMPTR_INVALID; }
> static inline void nested_evmcs_filter_control_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata) {}
> static inline bool nested_evmcs_l2_tlb_flush_enabled(struct kvm_vcpu *vcpu) { return false; }
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index d0d735974b2c..b45586588bae 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -179,7 +179,7 @@ static int nested_vmx_failValid(struct kvm_vcpu *vcpu,
> * VM_INSTRUCTION_ERROR is not shadowed. Enlightened VMCS 'shadows' all
> * fields and thus must be synced.
> */
> - if (to_vmx(vcpu)->nested.hv_evmcs_vmptr != EVMPTR_INVALID)
> + if (nested_vmx_evmptr12(to_vmx(vcpu)) != EVMPTR_INVALID)
> to_vmx(vcpu)->nested.need_vmcs12_to_shadow_sync = true;
>
> return kvm_skip_emulated_instruction(vcpu);
> @@ -194,7 +194,7 @@ static int nested_vmx_fail(struct kvm_vcpu *vcpu, u32 vm_instruction_error)
> * can't be done if there isn't a current VMCS.
> */
> if (vmx->nested.current_vmptr == INVALID_GPA &&
> - !evmptr_is_valid(vmx->nested.hv_evmcs_vmptr))
> + !nested_vmx_is_evmptr12_valid(vmx))
> return nested_vmx_failInvalid(vcpu);
>
> return nested_vmx_failValid(vcpu, vm_instruction_error);
> @@ -230,7 +230,7 @@ static inline void nested_release_evmcs(struct kvm_vcpu *vcpu)
> struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
> struct vcpu_vmx *vmx = to_vmx(vcpu);
>
> - if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr)) {
> + if (nested_vmx_is_evmptr12_valid(vmx)) {
> kvm_vcpu_unmap(vcpu, &vmx->nested.hv_evmcs_map, true);
> vmx->nested.hv_evmcs = NULL;
> }
> @@ -2011,7 +2011,7 @@ static enum nested_evmptrld_status nested_vmx_handle_enlightened_vmptrld(
> return EVMPTRLD_DISABLED;
> }
>
> - if (unlikely(evmcs_gpa != vmx->nested.hv_evmcs_vmptr)) {
> + if (unlikely(evmcs_gpa != nested_vmx_evmptr12(vmx))) {
> vmx->nested.current_vmptr = INVALID_GPA;
>
> nested_release_evmcs(vcpu);
> @@ -2089,7 +2089,7 @@ void nested_sync_vmcs12_to_shadow(struct kvm_vcpu *vcpu)
> {
> struct vcpu_vmx *vmx = to_vmx(vcpu);
>
> - if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr))
> + if (nested_vmx_is_evmptr12_valid(vmx))
> copy_vmcs12_to_enlightened(vmx);
> else
> copy_vmcs12_to_shadow(vmx);
> @@ -2243,7 +2243,7 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct loaded_vmcs *vmcs0
> u32 exec_control;
> u64 guest_efer = nested_vmx_calc_efer(vmx, vmcs12);
>
> - if (vmx->nested.dirty_vmcs12 || evmptr_is_valid(vmx->nested.hv_evmcs_vmptr))
> + if (vmx->nested.dirty_vmcs12 || nested_vmx_is_evmptr12_valid(vmx))
> prepare_vmcs02_early_rare(vmx, vmcs12);
>
> /*
> @@ -2538,11 +2538,11 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
> struct vcpu_vmx *vmx = to_vmx(vcpu);
> bool load_guest_pdptrs_vmcs12 = false;
>
> - if (vmx->nested.dirty_vmcs12 || evmptr_is_valid(vmx->nested.hv_evmcs_vmptr)) {
> + if (vmx->nested.dirty_vmcs12 || nested_vmx_is_evmptr12_valid(vmx)) {
> prepare_vmcs02_rare(vmx, vmcs12);
> vmx->nested.dirty_vmcs12 = false;
>
> - load_guest_pdptrs_vmcs12 = !evmptr_is_valid(vmx->nested.hv_evmcs_vmptr) ||
> + load_guest_pdptrs_vmcs12 = !nested_vmx_is_evmptr12_valid(vmx) ||
> !(vmx->nested.hv_evmcs->hv_clean_fields &
> HV_VMX_ENLIGHTENED_CLEAN_FIELD_GUEST_GRP1);
> }
> @@ -2665,7 +2665,7 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
> * bits when it changes a field in eVMCS. Mark all fields as clean
> * here.
> */
> - if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr))
> + if (nested_vmx_is_evmptr12_valid(vmx))
> vmx->nested.hv_evmcs->hv_clean_fields |=
> HV_VMX_ENLIGHTENED_CLEAN_FIELD_ALL;
>
> @@ -3173,7 +3173,7 @@ static bool nested_get_evmcs_page(struct kvm_vcpu *vcpu)
> * properly reflected.
> */
> if (guest_cpuid_has_evmcs(vcpu) &&
> - vmx->nested.hv_evmcs_vmptr == EVMPTR_MAP_PENDING) {
> + nested_vmx_evmptr12(vmx) == EVMPTR_MAP_PENDING) {
> enum nested_evmptrld_status evmptrld_status =
> nested_vmx_handle_enlightened_vmptrld(vcpu, false);
>
> @@ -3543,7 +3543,7 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
>
> load_vmcs12_host_state(vcpu, vmcs12);
> vmcs12->vm_exit_reason = exit_reason.full;
> - if (enable_shadow_vmcs || evmptr_is_valid(vmx->nested.hv_evmcs_vmptr))
> + if (enable_shadow_vmcs || nested_vmx_is_evmptr12_valid(vmx))
> vmx->nested.need_vmcs12_to_shadow_sync = true;
> return NVMX_VMENTRY_VMEXIT;
> }
> @@ -3576,7 +3576,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
> if (CC(evmptrld_status == EVMPTRLD_VMFAIL))
> return nested_vmx_failInvalid(vcpu);
>
> - if (CC(!evmptr_is_valid(vmx->nested.hv_evmcs_vmptr) &&
> + if (CC(!nested_vmx_is_evmptr12_valid(vmx) &&
> vmx->nested.current_vmptr == INVALID_GPA))
> return nested_vmx_failInvalid(vcpu);
>
> @@ -3591,7 +3591,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
> if (CC(vmcs12->hdr.shadow_vmcs))
> return nested_vmx_failInvalid(vcpu);
>
> - if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr)) {
> + if (nested_vmx_is_evmptr12_valid(vmx)) {
> copy_enlightened_to_vmcs12(vmx, vmx->nested.hv_evmcs->hv_clean_fields);
> /* Enlightened VMCS doesn't have launch state */
> vmcs12->launch_state = !launch;
> @@ -4336,11 +4336,11 @@ static void sync_vmcs02_to_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
> {
> struct vcpu_vmx *vmx = to_vmx(vcpu);
>
> - if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr))
> + if (nested_vmx_is_evmptr12_valid(vmx))
> sync_vmcs02_to_vmcs12_rare(vcpu, vmcs12);
>
> vmx->nested.need_sync_vmcs02_to_vmcs12_rare =
> - !evmptr_is_valid(vmx->nested.hv_evmcs_vmptr);
> + !nested_vmx_is_evmptr12_valid(vmx);
>
> vmcs12->guest_cr0 = vmcs12_guest_cr0(vcpu, vmcs12);
> vmcs12->guest_cr4 = vmcs12_guest_cr4(vcpu, vmcs12);
> @@ -4861,7 +4861,7 @@ void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 vm_exit_reason,
> }
>
> if ((vm_exit_reason != -1) &&
> - (enable_shadow_vmcs || evmptr_is_valid(vmx->nested.hv_evmcs_vmptr)))
> + (enable_shadow_vmcs || nested_vmx_is_evmptr12_valid(vmx)))
> vmx->nested.need_vmcs12_to_shadow_sync = true;
>
> /* in case we halted in L2 */
> @@ -5327,7 +5327,7 @@ static int handle_vmclear(struct kvm_vcpu *vcpu)
> vmptr + offsetof(struct vmcs12,
> launch_state),
> &zero, sizeof(zero));
> - } else if (vmx->nested.hv_evmcs && vmptr == vmx->nested.hv_evmcs_vmptr) {
> + } else if (vmx->nested.hv_evmcs && vmptr == nested_vmx_evmptr12(vmx)) {
> nested_release_evmcs(vcpu);
> }
>
> @@ -5367,7 +5367,7 @@ static int handle_vmread(struct kvm_vcpu *vcpu)
> /* Decode instruction info and find the field to read */
> field = kvm_register_read(vcpu, (((instr_info) >> 28) & 0xf));
>
> - if (!evmptr_is_valid(vmx->nested.hv_evmcs_vmptr)) {
> + if (!nested_vmx_is_evmptr12_valid(vmx)) {
> /*
> * In VMX non-root operation, when the VMCS-link pointer is INVALID_GPA,
> * any VMREAD sets the ALU flags for VMfailInvalid.
> @@ -5593,7 +5593,7 @@ static int handle_vmptrld(struct kvm_vcpu *vcpu)
> return nested_vmx_fail(vcpu, VMXERR_VMPTRLD_VMXON_POINTER);
>
> /* Forbid normal VMPTRLD if Enlightened version was used */
> - if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr))
> + if (nested_vmx_is_evmptr12_valid(vmx))
> return 1;
>
> if (vmx->nested.current_vmptr != vmptr) {
> @@ -5656,7 +5656,7 @@ static int handle_vmptrst(struct kvm_vcpu *vcpu)
> if (!nested_vmx_check_permission(vcpu))
> return 1;
>
> - if (unlikely(evmptr_is_valid(to_vmx(vcpu)->nested.hv_evmcs_vmptr)))
> + if (unlikely(nested_vmx_is_evmptr12_valid(to_vmx(vcpu))))
> return 1;
>
> if (get_vmx_mem_address(vcpu, exit_qual, instr_info,
> @@ -6442,7 +6442,7 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
> kvm_state.size += sizeof(user_vmx_nested_state->vmcs12);
>
> /* 'hv_evmcs_vmptr' can also be EVMPTR_MAP_PENDING here */
> - if (vmx->nested.hv_evmcs_vmptr != EVMPTR_INVALID)
> + if (nested_vmx_evmptr12(vmx) != EVMPTR_INVALID)
> kvm_state.flags |= KVM_STATE_NESTED_EVMCS;
>
> if (is_guest_mode(vcpu) &&
> @@ -6498,7 +6498,7 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
> } else {
> copy_vmcs02_to_vmcs12_rare(vcpu, get_vmcs12(vcpu));
> if (!vmx->nested.need_vmcs12_to_shadow_sync) {
> - if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr))
> + if (nested_vmx_is_evmptr12_valid(vmx))
> /*
> * L1 hypervisor is not obliged to keep eVMCS
> * clean fields data always up-to-date while
> diff --git a/arch/x86/kvm/vmx/nested.h b/arch/x86/kvm/vmx/nested.h
> index b0f2e26c1aea..0cedb80c5c94 100644
> --- a/arch/x86/kvm/vmx/nested.h
> +++ b/arch/x86/kvm/vmx/nested.h
> @@ -58,7 +58,7 @@ static inline int vmx_has_valid_vmcs12(struct kvm_vcpu *vcpu)
>
> /* 'hv_evmcs_vmptr' can also be EVMPTR_MAP_PENDING here */
> return vmx->nested.current_vmptr != -1ull ||
> - vmx->nested.hv_evmcs_vmptr != EVMPTR_INVALID;
> + nested_vmx_evmptr12(vmx) != EVMPTR_INVALID;
> }
>
> static inline u16 nested_get_vpid02(struct kvm_vcpu *vcpu)

Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>

Best regards,
Maxim Levitsky

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