From: Paolo Bonzini <pbonzini@redhat.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Subject: [PATCH] KVM: x86: optimize check for valid PAT value
Date: Wed, 10 Apr 2019 11:55:26 +0200 [thread overview]
Message-ID: <1554890126-347-1-git-send-email-pbonzini@redhat.com> (raw)
This check will soon be done on every nested vmentry and vmexit,
"parallelize" it using bitwise operations.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/mtrr.c | 10 +---------
arch/x86/kvm/vmx/vmx.c | 2 +-
arch/x86/kvm/x86.h | 8 ++++++++
3 files changed, 10 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kvm/mtrr.c b/arch/x86/kvm/mtrr.c
index e9ea2d45ae66..9f72cc427158 100644
--- a/arch/x86/kvm/mtrr.c
+++ b/arch/x86/kvm/mtrr.c
@@ -48,11 +48,6 @@ static bool msr_mtrr_valid(unsigned msr)
return false;
}
-static bool valid_pat_type(unsigned t)
-{
- return t < 8 && (1 << t) & 0xf3; /* 0, 1, 4, 5, 6, 7 */
-}
-
static bool valid_mtrr_type(unsigned t)
{
return t < 8 && (1 << t) & 0x73; /* 0, 1, 4, 5, 6 */
@@ -67,10 +62,7 @@ bool kvm_mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data)
return false;
if (msr == MSR_IA32_CR_PAT) {
- for (i = 0; i < 8; i++)
- if (!valid_pat_type((data >> (i * 8)) & 0xff))
- return false;
- return true;
+ return kvm_pat_valid(data);
} else if (msr == MSR_MTRRdefType) {
if (data & ~0xcff)
return false;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index b6c533afbf27..b74679732cfc 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1891,7 +1891,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
break;
case MSR_IA32_CR_PAT:
if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) {
- if (!kvm_mtrr_valid(vcpu, MSR_IA32_CR_PAT, data))
+ if (!kvm_pat_valid(data))
return 1;
vmcs_write64(GUEST_IA32_PAT, data);
vcpu->arch.pat = data;
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 28406aa1136d..7bc7ac9d2a44 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -347,4 +347,12 @@ static inline void kvm_after_interrupt(struct kvm_vcpu *vcpu)
__this_cpu_write(current_vcpu, NULL);
}
+static inline bool kvm_pat_valid(u64 data)
+{
+ if (data & 0xF8F8F8F8F8F8F8F8)
+ return false;
+ /* 0, 1, 4, 5, 6, 7 are valid values. */
+ return (data | ((data & 0x0202020202020202) << 1)) == data;
+}
+
#endif
--
1.8.3.1
next reply other threads:[~2019-04-10 9:55 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-10 9:55 Paolo Bonzini [this message]
2019-04-10 12:55 ` [PATCH] KVM: x86: optimize check for valid PAT value David Laight
2019-04-10 14:57 ` Sean Christopherson
2019-04-10 17:09 ` Paolo Bonzini
2019-04-11 9:06 ` David Laight
2019-04-15 8:11 ` Paolo Bonzini
2019-04-15 9:03 ` David Laight
2019-04-10 14:58 ` Sean Christopherson
2019-04-10 23:36 ` Krish Sadhukhan
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