Re: [PATCH v4 21/21] KVM: selftests: Test READ=>WRITE dirty logging behavior for shadow MMU
From: Sean Christopherson <seanjc@google.com>
Date: 2026-01-08 20:29:11
Also in:
kvm, kvm-riscv, kvmarm, linux-riscv, lkml, loongarch
On Thu, Jan 08, 2026, Yosry Ahmed wrote:
On Thu, Jan 08, 2026 at 10:31:22AM -0800, Sean Christopherson wrote:quoted
On Thu, Jan 08, 2026, Yosry Ahmed wrote:quoted
quoted
/* - * Add an identity map for GVA range [0xc0000000, 0xc0002000). This + * Add an identity map for GVA range [0xc0000000, 0xc0004000). This * affects both L1 and L2. However... */ - virt_map(vm, GUEST_TEST_MEM, GUEST_TEST_MEM, TEST_MEM_PAGES); + virt_map(vm, TEST_MEM_BASE, TEST_MEM_BASE, TEST_MEM_PAGES); /* - * ... pages in the L2 GPA range [0xc0001000, 0xc0003000) will map to - * 0xc0000000. + * ... pages in the L2 GPA ranges [0xc0001000, 0xc0002000) and + * [0xc0003000, 0xc0004000) will map to 0xc0000000 and 0xc0001000 + * respectively.Are these ranges correct? I thought L2 GPA range [0xc0002000, 0xc0004000) will map to [0xc0000000, 0xc0002000).Gah, no. I looked at the comments after changing things around, but my eyes had glazed over by that point.quoted
Also, perhaps it's better to express those in terms of the macros? L2 GPA range [TEST_MEM_ALIAS_BASE, TEST_MEM_ALIAS_BASE + 2*PAGE_SIZE) will map to [TEST_MEM_BASE, TEST_MEM_BASE + 2*PAGE_SIZE)?Hmm, no, at some point we need to concretely state the addresses, so that people debugging this know what to expect, i.e. don't have to manually compute the addresses from the macros in order to debug.I was trying to avoid a situation where the comment gets out of sync with the macros in a way that gets confusing. Maybe reference both if it's not too verbose? /* * ... pages in the L2 GPA range [0xc0002000, 0xc0004000) at * TEST_MEM_ALIAS_BASE will map to [[0xc0000000, 0xc0002000) at * TEST_MEM_BASE. */
Heh, your solution to a mitigate a comment getting out of sync is to add more things to the comment that can get out of sync :-D Unless you feel very strongly about having the names of the macros in the comments, I'd prefer to keep just the raw addresses.