[PATCH] target-i386: fix losing XCR0 processor state component bits

Wanpeng Li
2016-09-28T05:31:20Z

From: Wanpeng Li <wanpeng.li@hotmail.com>

Commit 96193c22a "target-i386: Move xsave component mask to features array"
leverages features array to handle XCR0 processor state component bits,
however, it introduces a regression:

warning: host doesn't support requested feature: CPUID.0DH:EAX [bit 0]
warning: host doesn't support requested feature: CPUID.0DH:EAX [bit 1]
warning: host doesn't support requested feature: CPUID.0DH:EAX [bit 2]

My desktop doesn't have enough advance features, so just X87,SSE,AVX
warnings are splat when I boot a guest.

The get migratable flags logic in x86_cpu_filter_features() path will
filter out the feature flags which are unsupported and unmigratable.
However, the bits of XCR0 processor state component featureword don't
have feat_names, and some features like SSE/AVX etc have feat_names in
CPUID.01H:EDX, CPUID.01H:ECX, so they are treated as unsupported.

This patch fix it by don't filter out XCR0 processor state components
bits though they don't have feat_names just as before commit 96193c22ab3.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
target-i386/cpu.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index ad09246..9d24eff 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -2156,6 +2156,10 @@ static uint32_t x86_cpu_get_supported_feature_word(FeatureWord w,
r = kvm_arch_get_supported_cpuid(kvm_state, wi->cpuid_eax,
wi->cpuid_ecx,
wi->cpuid_reg);
+ if ((w == FEAT_XSAVE_COMP_LO) ||
+ (w == FEAT_XSAVE_COMP_HI)) {
+ return r;
+ }
} else if (tcg_enabled()) {
r = wi->tcg_features;
} else {
--
1.9.1