From ddff189f90e64407cae356212768f14d2a094257 Mon Sep 17 00:00:00 2001 From: Thomas Lamprecht Date: Mon, 24 Oct 2022 09:27:16 +0200 Subject: [PATCH] Revert "backport patch to fix TSC scaling for SVM" this was actually intended for the stable 5.15 branch, already included in 5.19. This reverts commit 198fde3a160b31b0661eef19ab96291b176f2c4e. Signed-off-by: Thomas Lamprecht --- ...-KVM-SVM-fix-tsc-scaling-cache-logic.patch | 113 ------------------ 1 file changed, 113 deletions(-) delete mode 100644 patches/kernel/0032-KVM-SVM-fix-tsc-scaling-cache-logic.patch diff --git a/patches/kernel/0032-KVM-SVM-fix-tsc-scaling-cache-logic.patch b/patches/kernel/0032-KVM-SVM-fix-tsc-scaling-cache-logic.patch deleted file mode 100644 index 15016ea..0000000 --- a/patches/kernel/0032-KVM-SVM-fix-tsc-scaling-cache-logic.patch +++ /dev/null @@ -1,113 +0,0 @@ -From 955c2b4d64593baecc87c64d1354cd5786975bd9 Mon Sep 17 00:00:00 2001 -From: Maxim Levitsky -Date: Mon, 6 Jun 2022 21:11:49 +0300 -Subject: [PATCH] KVM: SVM: fix tsc scaling cache logic - -SVM uses a per-cpu variable to cache the current value of the -tsc scaling multiplier msr on each cpu. - -Commit 1ab9287add5e2 -("KVM: X86: Add vendor callbacks for writing the TSC multiplier") -broke this caching logic. - -Refactor the code so that all TSC scaling multiplier writes go through -a single function which checks and updates the cache. - -This fixes the following scenario: - -1. A CPU runs a guest with some tsc scaling ratio. - -2. New guest with different tsc scaling ratio starts on this CPU - and terminates almost immediately. - - This ensures that the short running guest had set the tsc scaling ratio just - once when it was set via KVM_SET_TSC_KHZ. Due to the bug, - the per-cpu cache is not updated. - -3. The original guest continues to run, it doesn't restore the msr - value back to its own value, because the cache matches, - and thus continues to run with a wrong tsc scaling ratio. - -Fixes: 1ab9287add5e2 ("KVM: X86: Add vendor callbacks for writing the TSC multiplier") -Signed-off-by: Maxim Levitsky -Message-Id: <20220606181149.103072-1-mlevitsk@redhat.com> -Cc: stable@vger.kernel.org -Signed-off-by: Paolo Bonzini -[FE: backport, mainly dropped parts for the not yet present - 5228eb96a487 ("KVM: x86: nSVM: implement nested TSC scaling")] -Signed-off-by: Fiona Ebner ---- - arch/x86/kvm/svm/svm.c | 30 +++++++++++++++++++----------- - 1 file changed, 19 insertions(+), 11 deletions(-) - -diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c -index 938b9b24f0ee..ea87d06bdaba 100644 ---- a/arch/x86/kvm/svm/svm.c -+++ b/arch/x86/kvm/svm/svm.c -@@ -468,11 +468,24 @@ static int has_svm(void) - return 1; - } - -+void __svm_write_tsc_multiplier(u64 multiplier) -+{ -+ preempt_disable(); -+ -+ if (multiplier == __this_cpu_read(current_tsc_ratio)) -+ goto out; -+ -+ wrmsrl(MSR_AMD64_TSC_RATIO, multiplier); -+ __this_cpu_write(current_tsc_ratio, multiplier); -+out: -+ preempt_enable(); -+} -+ - static void svm_hardware_disable(void) - { - /* Make sure we clean up behind us */ - if (static_cpu_has(X86_FEATURE_TSCRATEMSR)) -- wrmsrl(MSR_AMD64_TSC_RATIO, TSC_RATIO_DEFAULT); -+ __svm_write_tsc_multiplier(TSC_RATIO_DEFAULT); - - cpu_svm_disable(); - -@@ -514,8 +527,7 @@ static int svm_hardware_enable(void) - wrmsrl(MSR_VM_HSAVE_PA, __sme_page_pa(sd->save_area)); - - if (static_cpu_has(X86_FEATURE_TSCRATEMSR)) { -- wrmsrl(MSR_AMD64_TSC_RATIO, TSC_RATIO_DEFAULT); -- __this_cpu_write(current_tsc_ratio, TSC_RATIO_DEFAULT); -+ __svm_write_tsc_multiplier(TSC_RATIO_DEFAULT); - } - - -@@ -1128,9 +1140,10 @@ static void svm_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset) - - static void svm_write_tsc_multiplier(struct kvm_vcpu *vcpu, u64 multiplier) - { -- wrmsrl(MSR_AMD64_TSC_RATIO, multiplier); -+ __svm_write_tsc_multiplier(multiplier); - } - -+ - /* Evaluate instruction intercepts that depend on guest CPUID features. */ - static void svm_recalc_instruction_intercepts(struct kvm_vcpu *vcpu, - struct vcpu_svm *svm) -@@ -1453,13 +1466,8 @@ static void svm_prepare_guest_switch(struct kvm_vcpu *vcpu) - vmsave(__sme_page_pa(sd->save_area)); - } - -- if (static_cpu_has(X86_FEATURE_TSCRATEMSR)) { -- u64 tsc_ratio = vcpu->arch.tsc_scaling_ratio; -- if (tsc_ratio != __this_cpu_read(current_tsc_ratio)) { -- __this_cpu_write(current_tsc_ratio, tsc_ratio); -- wrmsrl(MSR_AMD64_TSC_RATIO, tsc_ratio); -- } -- } -+ if (static_cpu_has(X86_FEATURE_TSCRATEMSR)) -+ __svm_write_tsc_multiplier(vcpu->arch.tsc_scaling_ratio); - - if (likely(tsc_aux_uret_slot >= 0)) - kvm_set_user_return_msr(tsc_aux_uret_slot, svm->tsc_aux, -1ull); --- -2.30.2 - -- 2.39.2