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Message-ID: <ZLqSH/lEbHEnQ9i8@google.com>
Date: Fri, 21 Jul 2023 07:11:43 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: isaku.yamahata@...el.com
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
isaku.yamahata@...il.com, Michael Roth <michael.roth@....com>,
Paolo Bonzini <pbonzini@...hat.com>, erdemaktas@...gle.com,
Sagi Shahar <sagis@...gle.com>,
David Matlack <dmatlack@...gle.com>,
Kai Huang <kai.huang@...el.com>,
Zhi Wang <zhi.wang.linux@...il.com>, chen.bo@...el.com,
linux-coco@...ts.linux.dev,
Chao Peng <chao.p.peng@...ux.intel.com>,
Ackerley Tng <ackerleytng@...gle.com>,
Vishal Annapurve <vannapurve@...gle.com>,
Yuan Yao <yuan.yao@...ux.intel.com>
Subject: Re: [RFC PATCH v4 04/10] KVM: x86: Introduce PFERR_GUEST_ENC_MASK to
indicate fault is private
s/Introduce/Use
This doesn't "introduce" anything, in the sense that it's an AMD-defined error
code flag. That matters because KVM *did* introduce/define PFERR_IMPLICIT_ACCESS.
On Thu, Jul 20, 2023, isaku.yamahata@...el.com wrote:
> From: Isaku Yamahata <isaku.yamahata@...el.com>
>
> Add two PFERR codes to designate that the page fault is private and that
> it requires looking up memory attributes. The vendor kvm page fault
> handler should set PFERR_GUEST_ENC_MASK bit based on their fault
> information. It may or may not use the hardware value directly or
> parse the hardware value to set the bit.
>
> For KVM_X86_PROTECTED_VM, ask memory attributes for the fault privateness.
...
> +static inline bool kvm_is_fault_private(struct kvm *kvm, gpa_t gpa, u64 error_code)
> +{
> + /*
> + * This is racy with mmu_seq. If we hit a race, it would result in a
> + * spurious KVM_EXIT_MEMORY_FAULT.
> + */
> + if (kvm->arch.vm_type == KVM_X86_SW_PROTECTED_VM)
> + return kvm_mem_is_private(kvm, gpa_to_gfn(gpa));
Please synthesize the error code flag for SW-protected VMs, same as TDX, e.g.
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 20e289e872eb..de9e0a9c41e6 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5751,6 +5751,10 @@ int noinline kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 err
if (WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root.hpa)))
return RET_PF_RETRY;
+ if (vcpu->kvm->arch.vm_type == KVM_X86_SW_PROTECTED_VM &&
+ kvm_mem_is_private(vcpu->kvm, gpa_to_gfn(cr2_or_gpa)))
+ error_code |= PFERR_GUEST_ENC_MASK;
+
r = RET_PF_INVALID;
if (unlikely(error_code & PFERR_RSVD_MASK)) {
r = handle_mmio_page_fault(vcpu, cr2_or_gpa, direct);
Functionally it's the same, but I want all VM types to have the same source of
truth for private versus shared, and I really don't want kvm_is_fault_private()
to exist.
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