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 v2 01/10] math64.h: Add mul_s64_u64_shr()
Date: Wed, 12 May 2021 16:09:36 +0100 [thread overview]
Message-ID: <20210512150945.4591-2-ilstam@amazon.com> (raw)
In-Reply-To: <20210512150945.4591-1-ilstam@amazon.com>
This function is needed for the nested TSC scaling code where we need to
multiply 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:[~2021-05-12 15:16 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-12 15:09 [PATCH v2 00/10] KVM: Implement nested TSC scaling Ilias Stamatis
2021-05-12 15:09 ` Ilias Stamatis [this message]
2021-05-18 22:36 ` [PATCH v2 01/10] math64.h: Add mul_s64_u64_shr() Sean Christopherson
2021-05-12 15:09 ` [PATCH v2 02/10] KVM: X86: Store L1's TSC scaling ratio in 'struct kvm_vcpu_arch' Ilias Stamatis
2021-05-18 22:52 ` Sean Christopherson
2021-05-19 8:54 ` Stamatis, Ilias
2021-05-12 15:09 ` [PATCH v2 03/10] KVM: X86: Add kvm_scale_tsc_l1() and kvm_compute_tsc_offset_l1() Ilias Stamatis
2021-05-18 23:04 ` Sean Christopherson
2021-05-19 9:02 ` Stamatis, Ilias
2021-05-19 15:40 ` Sean Christopherson
2021-05-20 18:27 ` Stamatis, Ilias
2021-05-12 15:09 ` [PATCH v2 04/10] KVM: VMX: Add a TSC multiplier field in VMCS12 Ilias Stamatis
2021-05-12 15:09 ` [PATCH v2 05/10] KVM: X86: Add functions for retrieving L2 TSC fields from common code Ilias Stamatis
2021-05-12 15:09 ` [PATCH v2 06/10] KVM: X86: Add functions that calculate the 02 TSC offset and multiplier Ilias Stamatis
2021-05-18 23:21 ` Sean Christopherson
2021-05-19 10:15 ` Stamatis, Ilias
2021-05-12 15:09 ` [PATCH v2 07/10] KVM: X86: Move write_l1_tsc_offset() logic to common code and rename it Ilias Stamatis
2021-05-19 0:05 ` Sean Christopherson
2021-05-19 11:45 ` Stamatis, Ilias
2021-05-19 15:49 ` Sean Christopherson
2021-05-12 15:09 ` [PATCH v2 08/10] KVM: VMX: Set the TSC offset and multiplier on nested entry and exit Ilias Stamatis
2021-05-19 0:07 ` Sean Christopherson
2021-05-19 11:55 ` Stamatis, Ilias
2021-05-12 15:09 ` [PATCH v2 09/10] KVM: VMX: Expose TSC scaling to L2 Ilias Stamatis
2021-05-12 15:09 ` [PATCH v2 10/10] KVM: selftests: x86: Add vmx_nested_tsc_scaling_test Ilias Stamatis
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