From 83150f2932ec4712e2630009ac4a585d4aba7a9e Mon Sep 17 00:00:00 2001 From: Ilias Stamatis Date: Wed, 26 May 2021 19:44:14 +0100 Subject: [PATCH] KVM: X86: Add functions that calculate the nested TSC fields When L2 is entered we need to "merge" the TSC multiplier and TSC offset values of 01 and 12 together. The merging is done using the following equations: offset_02 = ((offset_01 * mult_12) >> shift_bits) + offset_12 mult_02 = (mult_01 * mult_12) >> shift_bits Where shift_bits is kvm_tsc_scaling_ratio_frac_bits. Signed-off-by: Ilias Stamatis Reviewed-by: Maxim Levitsky Message-Id: <20210526184418.28881-8-ilstam@amazon.com> Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_host.h | 2 ++ arch/x86/kvm/x86.c | 25 +++++++++++++++++++++++++ 2 files changed, 27 insertions(+) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 6ec00427c6fd..14546c30bc63 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1799,6 +1799,8 @@ static inline bool kvm_is_supported_user_return_msr(u32 msr) u64 kvm_scale_tsc(struct kvm_vcpu *vcpu, u64 tsc, u64 ratio); u64 kvm_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc); +u64 kvm_calc_nested_tsc_offset(u64 l1_offset, u64 l2_offset, u64 l2_multiplier); +u64 kvm_calc_nested_tsc_multiplier(u64 l1_multiplier, u64 l2_multiplier); unsigned long kvm_get_linear_rip(struct kvm_vcpu *vcpu); bool kvm_is_linear_rip(struct kvm_vcpu *vcpu, unsigned long linear_rip); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a6d46520b550..61024ee9e85f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2334,6 +2334,31 @@ u64 kvm_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc) } EXPORT_SYMBOL_GPL(kvm_read_l1_tsc); +u64 kvm_calc_nested_tsc_offset(u64 l1_offset, u64 l2_offset, u64 l2_multiplier) +{ + u64 nested_offset; + + if (l2_multiplier == kvm_default_tsc_scaling_ratio) + nested_offset = l1_offset; + else + nested_offset = mul_s64_u64_shr((s64) l1_offset, l2_multiplier, + kvm_tsc_scaling_ratio_frac_bits); + + nested_offset += l2_offset; + return nested_offset; +} +EXPORT_SYMBOL_GPL(kvm_calc_nested_tsc_offset); + +u64 kvm_calc_nested_tsc_multiplier(u64 l1_multiplier, u64 l2_multiplier) +{ + if (l2_multiplier != kvm_default_tsc_scaling_ratio) + return mul_u64_u64_shr(l1_multiplier, l2_multiplier, + kvm_tsc_scaling_ratio_frac_bits); + + return l1_multiplier; +} +EXPORT_SYMBOL_GPL(kvm_calc_nested_tsc_multiplier); + static void kvm_vcpu_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset) { vcpu->arch.l1_tsc_offset = offset;