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 <t.lamprecht@proxmox.com>

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 (file)
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 <mlevitsk@redhat.com>
-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 <mlevitsk@redhat.com>
-Message-Id: <20220606181149.103072-1-mlevitsk@redhat.com>
-Cc: stable@vger.kernel.org
-Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-[FE: backport, mainly dropped parts for the not yet present
-     5228eb96a487 ("KVM: x86: nSVM: implement nested TSC scaling")]
-Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
----
- 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
-