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| author | Michael Kelley <mhklinux@outlook.com> | 2025-03-19 00:49:19 +0300 |
|---|---|---|
| committer | Wei Liu <wei.liu@kernel.org> | 2025-03-21 21:24:22 +0300 |
| commit | 999ad14259a0d45cb3b616e2e95a7c8b622a7ecd (patch) | |
| tree | 177df3483f8dd8f22d1a84354a5e08bc84b17d90 /arch/x86/hyperv | |
| parent | 621191d709b14882270dfd8ea5d7d6cdfebe2c35 (diff) | |
| download | linux-999ad14259a0d45cb3b616e2e95a7c8b622a7ecd.tar.xz | |
x86/hyperv: Add comments about hv_vpset and var size hypercall input args
Current code varies in how the size of the variable size input header
for hypercalls is calculated when the input contains struct hv_vpset.
Surprisingly, this variation is correct, as different hypercalls make
different choices for what portion of struct hv_vpset is treated as part
of the variable size input header. The Hyper-V TLFS is silent on these
details, but the behavior has been confirmed with Hyper-V developers.
To avoid future confusion about these differences, add comments to
struct hv_vpset, and to hypercall call sites with input that contains
a struct hv_vpset. The comments describe the overall situation and
the calculation that should be used at each particular call site.
No functional change as only comments are updated.
Signed-off-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/20250318214919.958953-1-mhklinux@outlook.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20250318214919.958953-1-mhklinux@outlook.com>
Diffstat (limited to 'arch/x86/hyperv')
| -rw-r--r-- | arch/x86/hyperv/hv_apic.c | 5 | ||||
| -rw-r--r-- | arch/x86/hyperv/mmu.c | 4 |
2 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c index f022d5f64fb6..6d91ac5f9836 100644 --- a/arch/x86/hyperv/hv_apic.c +++ b/arch/x86/hyperv/hv_apic.c @@ -145,6 +145,11 @@ static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector, ipi_arg->vp_set.format = HV_GENERIC_SET_ALL; } + /* + * For this hypercall, Hyper-V treats the valid_bank_mask field + * of ipi_arg->vp_set as part of the fixed size input header. + * So the variable input header size is equal to nr_bank. + */ status = hv_do_rep_hypercall(HVCALL_SEND_IPI_EX, 0, nr_bank, ipi_arg, NULL); diff --git a/arch/x86/hyperv/mmu.c b/arch/x86/hyperv/mmu.c index cc8c3bd0e7c2..80d9350612d2 100644 --- a/arch/x86/hyperv/mmu.c +++ b/arch/x86/hyperv/mmu.c @@ -205,6 +205,10 @@ static u64 hyperv_flush_tlb_others_ex(const struct cpumask *cpus, /* * We can flush not more than max_gvas with one hypercall. Flush the * whole address space if we were asked to do more. + * + * For these hypercalls, Hyper-V treats the valid_bank_mask field + * of flush->hv_vp_set as part of the fixed size input header. + * So the variable input header size is equal to nr_bank. */ max_gvas = (PAGE_SIZE - sizeof(*flush) - nr_bank * |