From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2 10/15] KVM: VMX: Move uret MSR lookup into update_transition_efer()
Date: Wed, 23 Sep 2020 11:04:04 -0700 [thread overview]
Message-ID: <20200923180409.32255-11-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20200923180409.32255-1-sean.j.christopherson@intel.com>
Move checking for the existence of MSR_EFER in the uret MSR array into
update_transition_efer() so that the lookup and manipulation of the
array in setup_msrs() occur back-to-back. This paves the way toward
adding a helper to wrap the lookup and manipulation.
To avoid unnecessary overhead, defer the lookup until the uret array
would actually be modified in update_transition_efer(). EFER obviously
exists on CPUs that support the dedicated VMCS fields for switching
EFER, and EFER must exist for the guest and host EFER.NX value to
diverge, i.e. there is no danger of attempting to read/write EFER when
it doesn't exist.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kvm/vmx/vmx.c | 35 +++++++++++++++++++++--------------
1 file changed, 21 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index ed9ce25d3807..f3192855f0fb 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -953,10 +953,11 @@ static void add_atomic_switch_msr(struct vcpu_vmx *vmx, unsigned msr,
m->host.val[j].value = host_val;
}
-static bool update_transition_efer(struct vcpu_vmx *vmx, int efer_offset)
+static bool update_transition_efer(struct vcpu_vmx *vmx)
{
u64 guest_efer = vmx->vcpu.arch.efer;
u64 ignore_bits = 0;
+ int i;
/* Shadow paging assumes NX to be available. */
if (!enable_ept)
@@ -988,17 +989,21 @@ static bool update_transition_efer(struct vcpu_vmx *vmx, int efer_offset)
else
clear_atomic_switch_msr(vmx, MSR_EFER);
return false;
- } else {
- clear_atomic_switch_msr(vmx, MSR_EFER);
-
- guest_efer &= ~ignore_bits;
- guest_efer |= host_efer & ignore_bits;
-
- vmx->guest_uret_msrs[efer_offset].data = guest_efer;
- vmx->guest_uret_msrs[efer_offset].mask = ~ignore_bits;
-
- return true;
}
+
+ i = __vmx_find_uret_msr(vmx, MSR_EFER);
+ if (i < 0)
+ return false;
+
+ clear_atomic_switch_msr(vmx, MSR_EFER);
+
+ guest_efer &= ~ignore_bits;
+ guest_efer |= host_efer & ignore_bits;
+
+ vmx->guest_uret_msrs[i].data = guest_efer;
+ vmx->guest_uret_msrs[i].mask = ~ignore_bits;
+
+ return true;
}
#ifdef CONFIG_X86_32
@@ -1719,9 +1724,11 @@ static void setup_msrs(struct vcpu_vmx *vmx)
move_msr_up(vmx, index, nr_active_uret_msrs++);
}
#endif
- index = __vmx_find_uret_msr(vmx, MSR_EFER);
- if (index >= 0 && update_transition_efer(vmx, index))
- move_msr_up(vmx, index, nr_active_uret_msrs++);
+ if (update_transition_efer(vmx)) {
+ index = __vmx_find_uret_msr(vmx, MSR_EFER);
+ if (index >= 0)
+ move_msr_up(vmx, index, nr_active_uret_msrs++);
+ }
if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDTSCP)) {
index = __vmx_find_uret_msr(vmx, MSR_TSC_AUX);
if (index >= 0)
--
2.28.0
next prev parent reply other threads:[~2020-09-23 18:04 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-23 18:03 [PATCH v2 00/15] KVM: x86: VMX: Fix MSR namespacing Sean Christopherson
2020-09-23 18:03 ` [PATCH v2 01/15] KVM: x86: Rename "shared_msrs" to "user_return_msrs" Sean Christopherson
2020-09-23 18:03 ` [PATCH v2 02/15] KVM: VMX: Prepend "MAX_" to MSR array size defines Sean Christopherson
2020-09-23 18:03 ` [PATCH v2 03/15] KVM: VMX: Rename "vmx_find_msr_index" to "vmx_find_loadstore_msr_slot" Sean Christopherson
2020-09-25 22:04 ` Paolo Bonzini
2020-09-23 18:03 ` [PATCH v2 04/15] KVM: VMX: Rename the "shared_msr_entry" struct to "vmx_uret_msr" Sean Christopherson
2020-09-23 18:03 ` [PATCH v2 05/15] KVM: VMX: Rename vcpu_vmx's "nmsrs" to "nr_uret_msrs" Sean Christopherson
2020-09-23 18:04 ` [PATCH v2 06/15] KVM: VMX: Rename vcpu_vmx's "save_nmsrs" to "nr_active_uret_msrs" Sean Christopherson
2020-09-23 18:04 ` [PATCH v2 07/15] KVM: VMX: Rename vcpu_vmx's "guest_msrs_ready" to "guest_uret_msrs_loaded" Sean Christopherson
2020-09-23 18:04 ` [PATCH v2 08/15] KVM: VMX: Rename "__find_msr_index" to "__vmx_find_uret_msr" Sean Christopherson
2020-09-23 18:04 ` [PATCH v2 09/15] KVM: VMX: Check guest support for RDTSCP before processing MSR_TSC_AUX Sean Christopherson
2020-09-23 18:04 ` Sean Christopherson [this message]
2020-09-23 18:04 ` [PATCH v2 11/15] KVM: VMX: Add vmx_setup_uret_msr() to handle lookup and swap Sean Christopherson
2020-09-23 18:04 ` [PATCH v2 12/15] KVM: VMX: Rename "find_msr_entry" to "vmx_find_uret_msr" Sean Christopherson
2020-09-23 18:04 ` [PATCH v2 13/15] KVM: VMX: Rename "vmx_set_guest_msr" to "vmx_set_guest_uret_msr" Sean Christopherson
2020-09-23 18:04 ` [PATCH v2 14/15] KVM: VMX: Rename "vmx_msr_index" to "vmx_uret_msrs_list" Sean Christopherson
2020-09-23 18:04 ` [PATCH v2 15/15] KVM: VMX: Rename vmx_uret_msr's "index" to "slot" Sean Christopherson
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