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[PULL 12/13] target/i386: KVM: allow fast string operations if host supp
From: |
Paolo Bonzini |
Subject: |
[PULL 12/13] target/i386: KVM: allow fast string operations if host supports them |
Date: |
Mon, 27 Feb 2023 18:55:23 +0100 |
These are just a flag that documents the performance characteristic of
an instruction; it needs no hypervisor support. So include them even
if KVM does not show them. In particular, FZRM/FSRS/FSRC have only
been added very recently, but they are available on Sapphire Rapids
processors.
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
target/i386/kvm/kvm.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 587030199192..d18bd2f3e889 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -352,7 +352,7 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uint32_t
function,
{
struct kvm_cpuid2 *cpuid;
uint32_t ret = 0;
- uint32_t cpuid_1_edx;
+ uint32_t cpuid_1_edx, unused;
uint64_t bitmask;
cpuid = get_supported_cpuid(s);
@@ -399,10 +399,20 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s,
uint32_t function,
} else if (function == 6 && reg == R_EAX) {
ret |= CPUID_6_EAX_ARAT; /* safe to allow because of emulated APIC */
} else if (function == 7 && index == 0 && reg == R_EBX) {
+ /* Not new instructions, just an optimization. */
+ uint32_t ebx;
+ host_cpuid(7, 0, &unused, &ebx, &unused, &unused);
+ ret |= ebx & CPUID_7_0_EBX_ERMS;
+
if (host_tsx_broken()) {
ret &= ~(CPUID_7_0_EBX_RTM | CPUID_7_0_EBX_HLE);
}
} else if (function == 7 && index == 0 && reg == R_EDX) {
+ /* Not new instructions, just an optimization. */
+ uint32_t edx;
+ host_cpuid(7, 0, &unused, &unused, &unused, &edx);
+ ret |= edx & CPUID_7_0_EDX_FSRM;
+
/*
* Linux v4.17-v4.20 incorrectly return ARCH_CAPABILITIES on SVM hosts.
* We can detect the bug by checking if MSR_IA32_ARCH_CAPABILITIES is
@@ -411,6 +421,11 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s,
uint32_t function,
if (!has_msr_arch_capabs) {
ret &= ~CPUID_7_0_EDX_ARCH_CAPABILITIES;
}
+ } else if (function == 7 && index == 1 && reg == R_EAX) {
+ /* Not new instructions, just an optimization. */
+ uint32_t eax;
+ host_cpuid(7, 1, &eax, &unused, &unused, &unused);
+ ret |= eax & (CPUID_7_1_EAX_FZRM | CPUID_7_1_EAX_FSRS |
CPUID_7_1_EAX_FSRC);
} else if (function == 0xd && index == 0 &&
(reg == R_EAX || reg == R_EDX)) {
/*
--
2.39.1
- [PULL 02/13] meson: Avoid duplicates in generated config-poison.h again, (continued)
- [PULL 02/13] meson: Avoid duplicates in generated config-poison.h again, Paolo Bonzini, 2023/02/27
- [PULL 03/13] meson: stop looking for 'sphinx-build-3', Paolo Bonzini, 2023/02/27
- [PULL 04/13] configure: protect against escaping venv when running Meson, Paolo Bonzini, 2023/02/27
- [PULL 05/13] configure: Look for auxiliary Python installations, Paolo Bonzini, 2023/02/27
- [PULL 06/13] lcitool: update submodule, Paolo Bonzini, 2023/02/27
- [PULL 07/13] docs/devel: update and clarify lcitool instructions, Paolo Bonzini, 2023/02/27
- [PULL 08/13] ci, docker: update CentOS and OpenSUSE Python to non-EOL versions, Paolo Bonzini, 2023/02/27
- [PULL 09/13] MAINTAINERS: Cover RCU documentation, Paolo Bonzini, 2023/02/27
- [PULL 10/13] target/i386: add FSRM to TCG, Paolo Bonzini, 2023/02/27
- [PULL 11/13] target/i386: add FZRM, FSRS, FSRC, Paolo Bonzini, 2023/02/27
- [PULL 12/13] target/i386: KVM: allow fast string operations if host supports them,
Paolo Bonzini <=
- Re: [PULL 00/13] build, Python, target/i386 changes for 2023-02-27, Peter Maydell, 2023/02/28