At present, in KVM, x86_ext_save_areas[] is initialized based on Host CPUIDs.
Except AMX xstates, both user & supervisor xstates have their information exposed in KVM_GET_SUPPORTED_CPUID. Therefore, their entries in x86_ext_save_areas[] should be filled based on KVM support. For AMX xstates (XFEATURE_MASK_XTILE_DATA and XFEATURE_MASK_XTILE_CFG), KVM doesn't report their details before they (mainly XSTATE_XTILE_DATA_MASK) get permission on host. But this happens within the function kvm_request_xsave_components(), after the current initialization. So still fill AMX entries with Host CPUIDs. In addition, drop a check: "if (eax != 0)" when assert the assert the size of xstate. In fact, this check is incorrect, since any valid xstate should have non-zero size of xstate area. Tested-by: Farrah Chen <[email protected]> Signed-off-by: Zhao Liu <[email protected]> --- Changes Since v3: - New commit. --- target/i386/cpu.h | 3 +++ target/i386/kvm/kvm-cpu.c | 23 +++++++++++++++++------ 2 files changed, 20 insertions(+), 6 deletions(-) diff --git a/target/i386/cpu.h b/target/i386/cpu.h index 3d74afc5a8e7..f065527757c4 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -609,6 +609,9 @@ typedef enum X86Seg { #define XSTATE_DYNAMIC_MASK (XSTATE_XTILE_DATA_MASK) +#define XSTATE_XTILE_MASK (XSTATE_XTILE_DATA_MASK | \ + XSTATE_XTILE_CFG_MASK) + #define ESA_FEATURE_ALIGN64_BIT 1 #define ESA_FEATURE_XFD_BIT 2 diff --git a/target/i386/kvm/kvm-cpu.c b/target/i386/kvm/kvm-cpu.c index 9c25b5583955..2e2d47d2948a 100644 --- a/target/i386/kvm/kvm-cpu.c +++ b/target/i386/kvm/kvm-cpu.c @@ -136,7 +136,7 @@ static void kvm_cpu_max_instance_init(X86CPU *cpu) static void kvm_cpu_xsave_init(void) { static bool first = true; - uint32_t eax, ebx, ecx, edx; + uint32_t eax, ebx, ecx, unused; int i; if (!first) { @@ -154,12 +154,23 @@ static void kvm_cpu_xsave_init(void) if (!esa->size) { continue; } - host_cpuid(0xd, i, &eax, &ebx, &ecx, &edx); - if (eax != 0) { - assert(esa->size == eax); - esa->offset = ebx; - esa->ecx = ecx; + + /* + * AMX xstates are supported in KVM_GET_SUPPORTED_CPUID only when + * XSTATE_XTILE_DATA_MASK gets guest permission in + * kvm_request_xsave_components(). + */ + if (!((1 << i) & XSTATE_XTILE_MASK)) { + eax = kvm_arch_get_supported_cpuid(kvm_state, 0xd, i, R_EAX); + ebx = kvm_arch_get_supported_cpuid(kvm_state, 0xd, i, R_EBX); + ecx = kvm_arch_get_supported_cpuid(kvm_state, 0xd, i, R_ECX); + } else { + host_cpuid(0xd, i, &eax, &ebx, &ecx, &unused); } + + assert(esa->size == eax); + esa->offset = ebx; + esa->ecx = ecx; } } -- 2.34.1
