From: James Hogan <james.hogan@imgtec.com> To: <qemu-devel@nongnu.org> Cc: <kvm@vger.kernel.org>, Aurelien Jarno <aurelien@aurel32.net>, "Paolo Bonzini" <pbonzini@redhat.com>, James Hogan <james.hogan@imgtec.com> Subject: [PATCH v2 2/4] mips/kvm: Disable FPU on reset with KVM Date: Fri, 27 Jun 2014 16:22:42 +0100 [thread overview] Message-ID: <1403882562-28367-1-git-send-email-james.hogan@imgtec.com> (raw) In-Reply-To: <53AD568E.7090409@redhat.com> KVM doesn't yet support the MIPS FPU, or writing to the guest's Config1 register which contains the FPU implemented bit. Clear QEMU's version of that bit on reset and display a warning that the FPU has been disabled. The previous incorrect Config1 CP0 register value wasn't being passed to KVM yet, however we should ensure it is set correctly now to reduce the risk of breaking migration/loadvm to a future version of QEMU/Linux that does support it. Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Paolo Bonzini <pbonzini@redhat.com> --- A slight variation this time, which should handle the case of the user setting the CPU explicitly a bit better (previously only the default Malta CPU was changed). Look reasonable? Changes in v2: - Add a warning to alert user that FPU is disabled (Aurelien Jarno). - Slightly different approach. Disable the FPU on reset from KVM code instead of only changing the default CPU for Malta. This will then happen even if the user specifies the core type explicitly (and without having to modify any CPU definitions), but it does print a message on each reset. - Rewrite (and hopefully clarify) commit message. --- target-mips/kvm.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/target-mips/kvm.c b/target-mips/kvm.c index 844e5bbe5f92..97fd51a02f5c 100644 --- a/target-mips/kvm.c +++ b/target-mips/kvm.c @@ -61,6 +61,13 @@ int kvm_arch_init_vcpu(CPUState *cs) void kvm_mips_reset_vcpu(MIPSCPU *cpu) { + CPUMIPSState *env = &cpu->env; + + if (env->CP0_Config1 & (1 << CP0C1_FP)) { + fprintf(stderr, "Warning: FPU not supported with KVM, disabling\n"); + env->CP0_Config1 &= ~(1 << CP0C1_FP); + } + DPRINTF("%s\n", __func__); } -- 1.9.3
WARNING: multiple messages have this Message-ID (diff)
From: James Hogan <james.hogan@imgtec.com> To: qemu-devel@nongnu.org Cc: Paolo Bonzini <pbonzini@redhat.com>, James Hogan <james.hogan@imgtec.com>, Aurelien Jarno <aurelien@aurel32.net>, kvm@vger.kernel.org Subject: [Qemu-devel] [PATCH v2 2/4] mips/kvm: Disable FPU on reset with KVM Date: Fri, 27 Jun 2014 16:22:42 +0100 [thread overview] Message-ID: <1403882562-28367-1-git-send-email-james.hogan@imgtec.com> (raw) In-Reply-To: <53AD568E.7090409@redhat.com> KVM doesn't yet support the MIPS FPU, or writing to the guest's Config1 register which contains the FPU implemented bit. Clear QEMU's version of that bit on reset and display a warning that the FPU has been disabled. The previous incorrect Config1 CP0 register value wasn't being passed to KVM yet, however we should ensure it is set correctly now to reduce the risk of breaking migration/loadvm to a future version of QEMU/Linux that does support it. Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Paolo Bonzini <pbonzini@redhat.com> --- A slight variation this time, which should handle the case of the user setting the CPU explicitly a bit better (previously only the default Malta CPU was changed). Look reasonable? Changes in v2: - Add a warning to alert user that FPU is disabled (Aurelien Jarno). - Slightly different approach. Disable the FPU on reset from KVM code instead of only changing the default CPU for Malta. This will then happen even if the user specifies the core type explicitly (and without having to modify any CPU definitions), but it does print a message on each reset. - Rewrite (and hopefully clarify) commit message. --- target-mips/kvm.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/target-mips/kvm.c b/target-mips/kvm.c index 844e5bbe5f92..97fd51a02f5c 100644 --- a/target-mips/kvm.c +++ b/target-mips/kvm.c @@ -61,6 +61,13 @@ int kvm_arch_init_vcpu(CPUState *cs) void kvm_mips_reset_vcpu(MIPSCPU *cpu) { + CPUMIPSState *env = &cpu->env; + + if (env->CP0_Config1 & (1 << CP0C1_FP)) { + fprintf(stderr, "Warning: FPU not supported with KVM, disabling\n"); + env->CP0_Config1 &= ~(1 << CP0C1_FP); + } + DPRINTF("%s\n", __func__); } -- 1.9.3
next prev parent reply other threads:[~2014-06-27 15:23 UTC|newest] Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-06-26 9:44 [PATCH 0/4] QEMU MIPS KVM improvements for v2.1 James Hogan 2014-06-26 9:44 ` [Qemu-devel] " James Hogan 2014-06-26 9:44 ` [PATCH 1/4] mips/kvm: Init EBase to correct KSEG0 James Hogan 2014-06-26 9:44 ` [Qemu-devel] " James Hogan 2014-06-27 8:41 ` Aurelien Jarno 2014-06-27 8:41 ` [Qemu-devel] " Aurelien Jarno 2014-06-26 9:44 ` [PATCH 2/4] mips_malta: Change default KVM cpu to 24Kc (no FP) James Hogan 2014-06-26 9:44 ` [Qemu-devel] " James Hogan 2014-06-27 8:43 ` Aurelien Jarno 2014-06-27 8:43 ` [Qemu-devel] " Aurelien Jarno 2014-06-27 11:33 ` Paolo Bonzini 2014-06-27 11:33 ` [Qemu-devel] " Paolo Bonzini 2014-06-27 15:22 ` James Hogan [this message] 2014-06-27 15:22 ` [Qemu-devel] [PATCH v2 2/4] mips/kvm: Disable FPU on reset with KVM James Hogan 2014-06-26 9:44 ` [PATCH 3/4] mips_malta: Remove incorrect KVM T&E references James Hogan 2014-06-26 9:44 ` [Qemu-devel] " James Hogan 2014-06-27 8:43 ` Aurelien Jarno 2014-06-27 8:43 ` [Qemu-devel] " Aurelien Jarno 2014-06-26 9:44 ` [PATCH 4/4] mips_malta: Catch kernels linked at wrong address James Hogan 2014-06-26 9:44 ` [Qemu-devel] " James Hogan 2014-06-27 8:43 ` Aurelien Jarno 2014-06-27 8:43 ` [Qemu-devel] " Aurelien Jarno 2014-06-26 10:12 ` [PATCH 0/4] QEMU MIPS KVM improvements for v2.1 Paolo Bonzini 2014-06-26 10:12 ` [Qemu-devel] " Paolo Bonzini 2014-06-26 11:27 ` James Hogan 2014-06-26 11:27 ` [Qemu-devel] " James Hogan
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