From: Ilias Stamatis <ilstam@amazon.com>
To: <kvm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<pbonzini@redhat.com>
Cc: <mlevitsk@redhat.com>, <seanjc@google.com>, <vkuznets@redhat.com>,
<wanpengli@tencent.com>, <jmattson@google.com>, <joro@8bytes.org>,
<zamsden@gmail.com>, <mtosatti@redhat.com>, <dwmw@amazon.co.uk>,
<ilstam@amazon.com>
Subject: [PATCH v3 01/12] math64.h: Add mul_s64_u64_shr()
Date: Fri, 21 May 2021 11:24:38 +0100 [thread overview]
Message-ID: <20210521102449.21505-2-ilstam@amazon.com> (raw)
In-Reply-To: <20210521102449.21505-1-ilstam@amazon.com>
This function is needed for KVM's nested virtualization. The nested TSC
scaling implementation requires multiplying the signed TSC offset with
the unsigned TSC multiplier.
Signed-off-by: Ilias Stamatis <ilstam@amazon.com>
---
include/linux/math64.h | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/include/linux/math64.h b/include/linux/math64.h
index 66deb1fdc2ef..2928f03d6d46 100644
--- a/include/linux/math64.h
+++ b/include/linux/math64.h
@@ -3,6 +3,7 @@
#define _LINUX_MATH64_H
#include <linux/types.h>
+#include <linux/math.h>
#include <vdso/math64.h>
#include <asm/div64.h>
@@ -234,6 +235,24 @@ static inline u64 mul_u64_u64_shr(u64 a, u64 b, unsigned int shift)
#endif
+#ifndef mul_s64_u64_shr
+static inline u64 mul_s64_u64_shr(s64 a, u64 b, unsigned int shift)
+{
+ u64 ret;
+
+ /*
+ * Extract the sign before the multiplication and put it back
+ * afterwards if needed.
+ */
+ ret = mul_u64_u64_shr(abs(a), b, shift);
+
+ if (a < 0)
+ ret = -((s64) ret);
+
+ return ret;
+}
+#endif /* mul_s64_u64_shr */
+
#ifndef mul_u64_u32_div
static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 divisor)
{
--
2.17.1
next prev parent reply other threads:[~2021-05-21 10:26 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-21 10:24 [PATCH v3 00/12] KVM: Implement nested TSC scaling Ilias Stamatis
2021-05-21 10:24 ` Ilias Stamatis [this message]
2021-05-24 17:49 ` [PATCH v3 01/12] math64.h: Add mul_s64_u64_shr() Maxim Levitsky
2021-05-21 10:24 ` [PATCH v3 02/12] KVM: X86: Store L1's TSC scaling ratio in 'struct kvm_vcpu_arch' Ilias Stamatis
2021-05-24 17:49 ` Maxim Levitsky
2021-05-21 10:24 ` [PATCH v3 03/12] KVM: X86: Rename kvm_compute_tsc_offset() to kvm_compute_tsc_offset_l1() Ilias Stamatis
2021-05-24 14:21 ` Paolo Bonzini
2021-05-24 17:49 ` Maxim Levitsky
2021-05-21 10:24 ` [PATCH v3 04/12] KVM: X86: Add a ratio parameter to kvm_scale_tsc() Ilias Stamatis
2021-05-24 14:23 ` Paolo Bonzini
2021-05-24 15:48 ` Sean Christopherson
2021-05-24 15:56 ` Paolo Bonzini
2021-05-24 17:50 ` Maxim Levitsky
2021-05-21 10:24 ` [PATCH v3 05/12] KVM: VMX: Add a TSC multiplier field in VMCS12 Ilias Stamatis
2021-05-21 10:24 ` [PATCH v3 06/12] KVM: X86: Add functions for retrieving L2 TSC fields from common code Ilias Stamatis
2021-05-24 17:50 ` Maxim Levitsky
2021-05-21 10:24 ` [PATCH v3 07/12] KVM: X86: Add functions that calculate L2's TSC offset and multiplier Ilias Stamatis
2021-05-24 17:51 ` Maxim Levitsky
2021-05-21 10:24 ` [PATCH v3 08/12] KVM: X86: Move write_l1_tsc_offset() logic to common code and rename it Ilias Stamatis
2021-05-24 17:51 ` Maxim Levitsky
2021-05-21 10:24 ` [PATCH v3 09/12] KVM: VMX: Remove vmx->current_tsc_ratio and decache_tsc_multiplier() Ilias Stamatis
2021-05-24 17:53 ` Maxim Levitsky
2021-05-24 18:44 ` Sean Christopherson
2021-05-25 10:41 ` Stamatis, Ilias
2021-05-25 15:58 ` Sean Christopherson
2021-05-25 16:15 ` Paolo Bonzini
2021-05-25 16:34 ` Sean Christopherson
2021-05-25 17:34 ` Paolo Bonzini
2021-05-25 18:21 ` Sean Christopherson
2021-05-25 18:52 ` Stamatis, Ilias
2021-05-25 19:25 ` Stamatis, Ilias
2021-05-25 23:35 ` Sean Christopherson
2021-05-21 10:24 ` [PATCH v3 10/12] KVM: VMX: Set the TSC offset and multiplier on nested entry and exit Ilias Stamatis
2021-05-24 17:54 ` Maxim Levitsky
2021-05-25 16:05 ` Sean Christopherson
2021-05-21 10:24 ` [PATCH v3 11/12] KVM: VMX: Expose TSC scaling to L2 Ilias Stamatis
2021-05-21 10:24 ` [PATCH v3 12/12] KVM: selftests: x86: Add vmx_nested_tsc_scaling_test Ilias Stamatis
2021-05-24 17:55 ` Maxim Levitsky
2021-05-24 15:37 ` [PATCH v3 00/12] KVM: Implement nested TSC scaling Paolo Bonzini
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