Re: [PATCH 3/9] Implement GIF, clgi and stgi v5
Alexander Graf wrote:
This patch implements the GIF flag and the clgi and stgi instructions that
set this flag. Only if the flag is set (default), interrupts can be received by
the CPU.
To keep the information about that somewhere, this patch adds a new hidden
flags vector. that is used to store information that does not go into the
vmcb, but is SVM specific.
v2 moves the hflags to x86 generic code
v3 makes use of the new permission helper
Signed-off-by: Alexander Graf [EMAIL PROTECTED]
---
arch/x86/kvm/svm.c | 42 +++---
include/asm-x86/kvm_host.h |3 +++
2 files changed, 42 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index a00421b..62bfa2b 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -614,6 +614,8 @@ static void init_vmcb(struct vcpu_svm *svm)
save-cr4 = 0;
}
force_new_asid(svm-vcpu);
+
+ svm-vcpu.arch.hflags = HF_GIF_MASK;
}
static int svm_vcpu_reset(struct kvm_vcpu *vcpu)
@@ -1233,6 +1235,36 @@ static int nested_svm_do(struct vcpu_svm *svm,
return retval;
}
+static int stgi_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
+{
+ if (nested_svm_check_permissions(svm))
+ return 1;
+
+ svm-next_rip = kvm_rip_read(svm-vcpu) + 3;
+ skip_emulated_instruction(svm-vcpu);
+
+ svm-vcpu.arch.hflags |= HF_GIF_MASK;
+
+ return 1;
+}
It feels a little strange to see this here instead of an implementation
of stgi/clgi in x86_emulate. Any reason for not going that route?
GIF somehow needs exposure to userspace too, right? Otherwise, when
using -no-kernel-apic, userspace may try to inject an interrupt when the
guest cannot handle it, right?
Regards,
Anthony Liguori
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Re: [PATCH 3/9] Implement GIF, clgi and stgi v5
Anthony Liguori wrote:
+static int stgi_interception(struct vcpu_svm *svm, struct kvm_run
*kvm_run)
+{
It feels a little strange to see this here instead of an
implementation of stgi/clgi in x86_emulate. Any reason for not going
that route?
We already know the instruction is stgi, no need to go through the guest
page tables to fetch it. We do the same thing for all instructions for
which we have the length and all the information necessary to execute it.
GIF somehow needs exposure to userspace too, right? Otherwise, when
using -no-kernel-apic, userspace may try to inject an interrupt when
the guest cannot handle it, right?
Hmm, right, it needs to close the interrupt window.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
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Re: [PATCH 3/9] Implement GIF, clgi and stgi v5
On 30.10.2008, at 19:10, Avi Kivity wrote:
Anthony Liguori wrote:
+static int stgi_interception(struct vcpu_svm *svm, struct kvm_run
*kvm_run)
+{
It feels a little strange to see this here instead of an
implementation of stgi/clgi in x86_emulate. Any reason for not
going that route?
We already know the instruction is stgi, no need to go through the
guest page tables to fetch it. We do the same thing for all
instructions for which we have the length and all the information
necessary to execute it.
GIF somehow needs exposure to userspace too, right? Otherwise,
when using -no-kernel-apic, userspace may try to inject an
interrupt when the guest cannot handle it, right?
Hmm, right, it needs to close the interrupt window.
Yes, it's broken with -no-kernel-apic, since the userspace doesn't
know the window is closed. Any good suggestions here? Joerg and me
decided to just ignore the non-kernel-apic case, but if it's important
we might want to sync the hflags with userspace, so we can export the
GIF.
Alex
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Re: [PATCH 3/9] Implement GIF, clgi and stgi v5
Alexander Graf wrote: On 30.10.2008, at 19:10, Avi Kivity wrote: GIF somehow needs exposure to userspace too, right? Otherwise, when using -no-kernel-apic, userspace may try to inject an interrupt when the guest cannot handle it, right? Hmm, right, it needs to close the interrupt window. Yes, it's broken with -no-kernel-apic, since the userspace doesn't know the window is closed. Any good suggestions here? Joerg and me decided to just ignore the non-kernel-apic case, but if it's important we might want to sync the hflags with userspace, so we can export the GIF. Maybe abusing kvm_run-if_flag? Current, userspace treats if_flag as a boolean. If you stored GIF and eflags.IF in there, I believe old userspaces would just work. Regards, Anthony Liguori Alex -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 3/9] Implement GIF, clgi and stgi v5
Avi Kivity wrote:
Anthony Liguori wrote:
+static int stgi_interception(struct vcpu_svm *svm, struct kvm_run
*kvm_run)
+{
It feels a little strange to see this here instead of an
implementation of stgi/clgi in x86_emulate. Any reason for not going
that route?
We already know the instruction is stgi, no need to go through the
guest page tables to fetch it. We do the same thing for all
instructions for which we have the length and all the information
necessary to execute it.
Fair enough.
Regards,
Anthony Liguori
GIF somehow needs exposure to userspace too, right? Otherwise, when
using -no-kernel-apic, userspace may try to inject an interrupt when
the guest cannot handle it, right?
Hmm, right, it needs to close the interrupt window.
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the body of a message to [EMAIL PROTECTED]
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